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1. Multiples of 3 and 5
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Jesscici @ Fri, 26 Feb 2016,
Angry Armadillos @ Fri, 30 Jan 2015,
Prime Triplets @ Thu, 11 May 2017,
Method Man @ Thu, 31 May 2018,
Clojurians @ Thu, 27 Aug 2015,
Hung Like David Foster Wallace @ Thu, 12 Dec 2013,
Uno Punto @ Thu, 29 Aug 2013,
One Point @ Thu, 29 Aug 2013,
C# @ Thu, 29 Aug 2013,
Clojing Time @ Thu, 27 Feb 2014,
Not As Good As Clojure @ Thu, 29 Oct 2015,
Team this.Table @ Thu, 25 Jun 2015,
Four Balls @ Thu, 28 May 2015,
C++ @ Thu, 29 Aug 2013,
99 Problems @ Mon, 29 Apr 2013,
C @ Thu, 29 Aug 2013,
NASA @ Thu, 02 Apr 2015,
Rock Solid @ Thu, 02 Apr 2015,
1 @ Thu, 27 Mar 2014,
Python @ Fri, 26 Feb 2016,
PDV @ Fri, 26 Feb 2016,
Night Salamander @ Thu, 31 May 2018,
Mighty Morphin' Power Angers @ Fri, 30 Jan 2015,
Dragon Fruit @ Mon, 29 Apr 2013,
PotionMasters @ Thu, 25 Sep 2014,
Team SNAP! @ Thu, 31 Mar 2016,
Team🍕 @ Wed, 28 Sep 2016,
ShanMan @ Thu, 30 May 2013,
Higi @ Mon, 29 Apr 2013,
Tits McGee @ Thu, 12 Dec 2013,
Brian @ Thu, 30 May 2013,
Kepler @ Thu, 30 May 2013,
Geminy Cricket @ Thu, 28 May 2015,
We'll Tell You A Name Later @ Thu, 30 Jan 2014,
Sandstorm @ Thu, 30 Jan 2014,
Persona 4 @ Thu, 30 Oct 2014,
Candy Cane @ Thu, 12 Dec 2013,
Cauliflower @ Thu, 28 Jul 2016,
Fünke @ Thu, 30 May 2013,
I got %d problems but a %s ain't one @ Thu, 01 May 2014,
Team Beer @ Thu, 28 Aug 2014,
The 26ers @ Thu, 28 Jul 2016,
Precise Pangolin @ Thu, 29 May 2014,
Project Humbug @ Thu, 12 Dec 2013
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2. Even Fibonacci numbers
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🏏 @ Thu, 29 Mar 2018,
We'll Tell You A Name Later @ Thu, 30 Jan 2014,
One Point @ Thu, 29 Aug 2013,
Precise Pangolin @ Thu, 29 May 2014,
Higi @ Mon, 29 Apr 2013,
Sandstorm @ Thu, 30 Jan 2014,
C# @ Thu, 29 Aug 2013,
Candy Cane @ Thu, 12 Dec 2013,
Kepler @ Thu, 30 May 2013,
99 Problems @ Mon, 29 Apr 2013,
Team🍕 @ Wed, 28 Sep 2016,
Persona 4 @ Thu, 30 Oct 2014,
Rock Solid @ Thu, 02 Apr 2015,
Tits McGee @ Thu, 12 Dec 2013,
Team SNAP! @ Thu, 31 Mar 2016,
Not As Good As Clojure @ Thu, 29 Oct 2015,
Captain Squelch @ Thu, 27 Aug 2015,
ShanMan @ Thu, 30 May 2013,
Four Balls @ Thu, 28 May 2015,
Clojing Time @ Thu, 27 Feb 2014,
Dragon Fruit @ Mon, 29 Apr 2013,
Brian @ Thu, 30 May 2013,
C @ Thu, 29 Aug 2013,
max(pow(e,r)) @ Thu, 28 Aug 2014,
Hung Like David Foster Wallace @ Thu, 12 Dec 2013,
Geminy Cricket @ Thu, 28 May 2015,
NASA @ Thu, 02 Apr 2015,
PDV @ Fri, 26 Feb 2016,
Method Man @ Thu, 31 May 2018
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3. Largest prime factor
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North West @ Thu, 27 Jun 2013,
Persona 4 @ Thu, 30 Oct 2014,
Not As Good As Clojure @ Thu, 29 Oct 2015,
Dragon Fruit @ Mon, 29 Apr 2013,
🏏 @ Thu, 29 Mar 2018,
EOF TABLE @ Thu, 28 Dec 2017,
The Iterators @ Thu, 28 Dec 2017,
Chicken Burritos @ Thu, 27 Jun 2013,
Fudge Bar @ Thu, 27 Jun 2013,
Ruby Slippers @ Thu, 01 Aug 2013,
C# @ Thu, 29 Aug 2013,
Tits McGee @ Thu, 12 Dec 2013
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4. Largest palindrome product
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Smitha @ Thu, 31 May 2018,
99 Problems @ Mon, 29 Apr 2013,
North West @ Thu, 27 Jun 2013,
Chicken Burritos @ Thu, 27 Jun 2013,
Persona 4 @ Thu, 30 Oct 2014,
Kepler @ Thu, 30 May 2013,
Tits McGee @ Thu, 12 Dec 2013,
Angry Armadillos @ Fri, 30 Jan 2015
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5. Smallest multiple
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North West @ Thu, 27 Jun 2013,
Team Beer @ Thu, 28 Aug 2014,
max(pow(e,r)) @ Thu, 28 Aug 2014,
Higi @ Mon, 29 Apr 2013,
Strawberry Sample @ Thu, 29 May 2014,
Sandstorm @ Thu, 30 Jan 2014,
NASA @ Thu, 02 Apr 2015,
Tits McGee @ Thu, 12 Dec 2013,
Smitha @ Thu, 31 May 2018,
Bears @ Thu, 29 Aug 2013
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6. Sum square difference
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Smitha @ Thu, 31 May 2018,
max(pow(e,r)) @ Thu, 28 Aug 2014,
Team Awesome @ Thu, 28 Aug 2014,
C @ Thu, 29 Aug 2013,
Prime Triplets @ Thu, 11 May 2017,
We'll Tell You A Name Later @ Thu, 30 Jan 2014,
Persona 4 @ Thu, 30 Oct 2014,
Team This Table @ Thu, 28 Aug 2014,
Sandstorm @ Thu, 30 Jan 2014,
Team Beer @ Thu, 28 Aug 2014,
99 Problems @ Mon, 29 Apr 2013,
North West @ Thu, 27 Jun 2013,
Tits McGee @ Thu, 12 Dec 2013
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7. 10001st prime
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Angry Armadillos @ Fri, 30 Jan 2015,
No Ether @ Thurs, 26 Feb 2015,
Team This Table @ Thu, 28 Aug 2014,
North West @ Thu, 27 Jun 2013,
Higi @ Mon, 29 Apr 2013,
Vegetarian Kernel Sanders @ Thu, 31 Jul 2014,
The Julii @ Thu, 28 May 2015,
Team Beer @ Thu, 28 Aug 2014,
Swift @ Fri, 26 Feb 2016
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8. Largest product in a series
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Tits McGee @ Thu, 12 Dec 2013,
Team This Table @ Thu, 28 Aug 2014,
North West @ Thu, 27 Jun 2013,
C++ @ Thu, 29 Aug 2013,
Team f.lux @ Thu, 27 Oct 2016
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9. Special Pythagorean triplet
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Oiler @ Thu, 30 Jan 2014,
Team 🐍 @ Thu, 27 Oct 2016
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10. Summation of primes
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Mighty Morphin' Power Angers @ Fri, 30 Jan 2015,
Angry Armadillos @ Fri, 30 Jan 2015,
Mountain Dew @ Thu, 29 May 2014,
Swift @ Fri, 26 Feb 2016,
We'll Tell You A Name Later @ Thu, 30 Jan 2014,
North West @ Thu, 27 Jun 2013,
Team This Table @ Thu, 28 Aug 2014,
Tits McGee @ Thu, 12 Dec 2013,
Retro Secret Agents @ Thu, 30 Jan 2014,
Vegetarian Kernel Sanders @ Thu, 31 Jul 2014,
The Square Roots @ Fri, 30 Jan 2015
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11. Largest product in a grid
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Precise Pangolin @ Thu, 29 May 2014,
Team Huy @ Thu, 25 Jun 2015,
North West @ Thu, 27 Jun 2013,
Secret 🐿 @ Thu, 28 Dec 2017
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12. Highly divisible triangular number
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Secret 🐿++ @ Thu, 29 Jun 2017
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13. Large sum
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Team Bernie @ Thu, 31 Jul 2014,
Team Beer @ Thu, 28 Aug 2014,
North West @ Thu, 27 Jun 2013,
Team Awesome @ Thu, 28 Aug 2014,
AtomicAwesomePants @ Thu, 25 Sep 2014,
Secret 🐿++ @ Thu, 29 Jun 2017,
nerdBusters @ Wed, 19 Nov 2014
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14. Longest Collatz sequence
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Team Awesome @ Thu, 28 Aug 2014,
Strawberry Sample @ Thu, 29 May 2014,
North West @ Thu, 27 Jun 2013,
C++ @ Thu, 26 Sep 2013
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15. Lattice paths
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Back from Seoul @ Thu, 01 May 2014,
Programmers Just Want To Have Fun @ Thu, 30 Apr 2015,
Chuckles @ Thu, 27 Aug 2015,
Prime Triplets @ Thu, 11 May 2017
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16. Power digit sum
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99 Problems @ Mon, 29 Apr 2013,
Team Beer @ Thu, 28 Aug 2014,
AwesomeSauceChicken @ Thu, 25 Sep 2014,
Oiler @ Thu, 30 Jan 2014,
Team Bernie @ Thu, 31 Jul 2014,
The Square Roots @ Fri, 30 Jan 2015
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17. Number letter counts
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Secret Squirrel @ Thu, 01 Sep 2016,
Hot Sauce @ Thu, 30 Jan 2014,
99 Problems @ Mon, 29 Apr 2013
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18. Maximum path sum I
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Project Humbug @ Thu, 12 Dec 2013,
Vegetarian Kernel Sanders @ Thu, 31 Jul 2014
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19. Counting Sundays
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Joshua @ Thu, 29 May 2014,
Diablo @ Thu, 27 Feb 2014,
Awesome Monster @ Thu, 01 May 2014
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20. Factorial digit sum
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Kepler @ Thu, 30 May 2013,
Awesome Monster @ Thu, 01 May 2014,
I got %d problems but a %s ain't one @ Thu, 01 May 2014,
Team Awesome @ Thu, 28 Aug 2014,
Team Beer @ Thu, 28 Aug 2014,
Programmers Just Want To Have Fun @ Thu, 30 Apr 2015,
Team Bernie @ Thu, 31 Jul 2014,
99 Problems @ Mon, 29 Apr 2013,
Oiler @ Thu, 30 Jan 2014,
Ghostbusters @ Fri, 30 Jan 2015,
Mighty Morphin' Power Angers @ Fri, 30 Jan 2015
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21. Amicable numbers
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Project Humbug @ Thu, 12 Dec 2013,
U of I @ Thu, 01 Aug 2013,
Tits McGee @ Thu, 12 Dec 2013,
The 26ers @ Thu, 28 Jul 2016,
No Ether @ Thurs, 26 Feb 2015,
Programmers Just Want To Have Fun @ Thu, 30 Apr 2015,
The 43ers @ Thu, 28 Jan 2016
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22. Names scores
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Vegetarian Kernel Sanders @ Thu, 31 Jul 2014,
Team Bernie @ Thu, 31 Jul 2014,
Started From The Bottom @ Fri, 30 Jan 2015,
We'll Tell You A Name Later @ Thu, 30 Jan 2014
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23. Non-abundant sums
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Vegetarian Kernel Sanders @ Thu, 31 Jul 2014
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24. Lexicographic permutations
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Team Awesome @ Thu, 28 Aug 2014
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25. 1000-digit Fibonacci number
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Kitten Sprinkles @ Thu, 27 Aug 2015,
Diablo @ Thu, 27 Feb 2014,
Awesome Monster @ Thu, 01 May 2014,
North West @ Thu, 27 Jun 2013,
The Unknowns @ Thu, 26 May 2016,
Chicken Burritos @ Thu, 27 Jun 2013,
Secret 🐿 @ Wed, 28 Sep 2016,
Kepler @ Thu, 30 May 2013,
99 Problems @ Mon, 29 Apr 2013,
Team Awesome @ Thu, 28 Aug 2014,
Nameless @ Thu, 31 Jul 2014,
Oiler @ Thu, 30 Jan 2014,
The Steves @ Thu, 30 Jan 2014
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26. Reciprocal cycles
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The 26ers @ Thu, 28 Jul 2016
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27. Quadratic primes
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🍝🍝🍝 @ Wed, 28 Sep 2016
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28. Number spiral diagonals
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SubjectiveC @ Thu, 25 Sep 2014
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29. Distinct powers
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Chicken Burritos @ Thu, 27 Jun 2013,
Awesome Monster @ Thu, 01 May 2014
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30. Digit fifth powers
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Chicken Burritos @ Thu, 27 Jun 2013,
99 Problems @ Mon, 29 Apr 2013,
C++ @ Thu, 29 Aug 2013,
Team Bernie @ Thu, 31 Jul 2014,
3 @ Thu, 27 Mar 2014
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31. Coin sums
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Vegetarian Kernel Sanders @ Thu, 31 Jul 2014,
R Marks The Spot @ Thu, 31 May 2018,
Kepler @ Thu, 30 May 2013,
Chicken Burritos @ Thu, 27 Jun 2013
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32. Pandigital products
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33. Digit canceling fractions
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Secret 🐿 @ Thu, 26 Jan 2017
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34. Digit factorials
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AtomicAwesomePants @ Thu, 25 Sep 2014,
Oiler @ Thu, 30 Jan 2014,
Chicken Burritos @ Thu, 27 Jun 2013,
C++ @ Thu, 29 Aug 2013,
C++ @ Thu, 26 Sep 2013,
Team Awesome @ Thu, 28 Aug 2014
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35. Circular primes
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Team This Table @ Thu, 28 Aug 2014
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36. Double-base palindromes
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SubjectiveC @ Thu, 25 Sep 2014,
I got %d problems but a %s ain't one @ Thu, 01 May 2014,
Team Awesome @ Thu, 28 Aug 2014
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37. Truncatable primes
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SubjectiveC @ Thu, 25 Sep 2014,
Veggiecadres @ Wed, 19 Nov 2014
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38. Pandigital multiples
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SubjectiveC @ Thu, 25 Sep 2014
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39. Integer right triangles
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Project Humbug @ Thu, 12 Dec 2013
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40. Champernowne's constant
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Spencer @ Thu, 28 Jul 2016
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41. Pandigital prime
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The Triad @ Thu, 17 Aug 2017,
Spencer @ Thu, 28 Jul 2016
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42. Coded triangle numbers
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Secret 🐿 @ Thu, 12 Oct 2017,
Spencer @ Thu, 28 Jul 2016,
Chuckles @ Thu, 27 Aug 2015
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43. Sub-string divisibility
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The 43ers @ Thu, 28 Jan 2016
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44. Pentagon numbers
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Nameless @ Thu, 31 Jul 2014
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45. Triangular, pentagonal, and hexagonal
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Secret 🐿 @ Thu, 27 Oct 2016
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46. Goldbach's other conjecture
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Chicken Burritos @ Thu, 27 Jun 2013
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47. Distinct primes factors
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ℚ² @ Thu, 29 Jun 2017,
C++ @ Thu, 29 Aug 2013
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48. Self powers
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I got %d problems but a %s ain't one @ Thu, 01 May 2014,
AtomicAwesomePants @ Thu, 25 Sep 2014,
Fünke @ Thu, 30 May 2013,
Team This Table @ Thu, 28 Aug 2014,
The Square Roots @ Fri, 30 Jan 2015,
Chicken Burritos @ Thu, 27 Jun 2013,
99 Problems @ Mon, 29 Apr 2013,
North West @ Thu, 27 Jun 2013,
Awesome Monster @ Thu, 01 May 2014,
Mighty Morphin' Power Angers @ Fri, 30 Jan 2015,
Oiler @ Thu, 30 Jan 2014,
Ghostbusters @ Fri, 30 Jan 2015,
Honeybadger Don't Care @ Thu, 29 May 2014,
3 @ Thu, 27 Mar 2014
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49. Prime permutations
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Hung Like David Foster Wallace @ Thu, 12 Dec 2013,
Higi @ Mon, 29 Apr 2013,
Team This Table @ Thu, 28 Aug 2014,
3 @ Thu, 27 Mar 2014
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50. Consecutive prime sum
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Chicken Burritos @ Thu, 27 Jun 2013,
Project Humbug @ Thu, 12 Dec 2013,
Team This Table @ Thu, 28 Aug 2014
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51. Prime digit replacements
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52. Permuted multiples
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Secret 🐿 @ Thu, 12 Oct 2017,
Team This Table @ Thu, 28 Aug 2014,
Higi @ Mon, 29 Apr 2013,
The Steves @ Thu, 30 Jan 2014,
Oiler @ Thu, 30 Jan 2014,
3 @ Thu, 27 Mar 2014,
Back from Seoul @ Thu, 01 May 2014
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53. Combinatoric selections
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Kitten Sprinkles @ Thu, 27 Aug 2015,
The Chargers @ Thu, 15 Jun 2017,
Oiler @ Thu, 30 Jan 2014,
Project Humbug @ Thu, 12 Dec 2013,
Back from Seoul @ Thu, 01 May 2014,
Just For Fun @ Mon, 29 Apr 2013
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54. Poker hands
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55. Lychrel numbers
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1 2 3 4 @ Thu, 30 May 2013,
The Chargers @ Thu, 15 Jun 2017
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56. Powerful digit sum
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Secret 🐿 @ Thu, 12 Oct 2017,
We Hate Primes @ Thu, 27 Mar 2014,
AwesomeSauceChicken @ Thu, 25 Sep 2014,
Nameless @ Thu, 31 Jul 2014,
Oiler @ Thu, 30 Jan 2014
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57. Square root convergents
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58. Spiral primes
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59. XOR decryption
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Fünke @ Thu, 30 May 2013,
Secret 🐿 @ Thu, 27 Oct 2016
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60. Prime pair sets
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61. Cyclical figurate numbers
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Mickey @ Thu, 28 Dec 2017
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62. Cubic permutations
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Mickey @ Thu, 28 Dec 2017,
The Chargers @ Thu, 15 Jun 2017
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63. Powerful digit counts
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🐿+🐢 @ Thu, 14 Sep 2017,
Mickey @ Thu, 28 Dec 2017
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64. Odd period square roots
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65. Convergents of e
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66. Diophantine equation
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67. Maximum path sum II
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Project Humbug @ Thu, 12 Dec 2013,
Honeybadger Don't Care @ Thu, 29 May 2014,
Vegetarian Kernel Sanders @ Thu, 31 Jul 2014,
Just For Fun @ Mon, 29 Apr 2013,
Mighty Morphin' Power Angers @ Fri, 30 Jan 2015
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68. Magic 5-gon ring
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69. Totient maximum
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Infinite Sadness @ Thu, 30 Apr 2015,
Lone Prime @ Thu, 15 Jun 2017
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70. Totient permutation
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71. Ordered fractions
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72. Counting fractions
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73. Counting fractions in a range
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74. Digit factorial chains
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75. Singular integer right triangles
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76. Counting summations
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77. Prime summations
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78. Coin partitions
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79. Passcode derivation
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Fünke @ Thu, 30 May 2013,
Team 🐍 @ Thu, 27 Oct 2016
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80. Square root digital expansion
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81. Path sum: two ways
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Emerald Vipers @ Thu, 30 Apr 2015,
Awesome Monster @ Thu, 01 May 2014
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82. Path sum: three ways
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Mountain Dew @ Thu, 29 May 2014
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83. Path sum: four ways
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84. Monopoly odds
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85. Counting rectangles
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sp00ky @ Thu, 26 Oct 2017,
Secret 🐿 @ Thu, 29 Mar 2018,
Awesome Monster @ Thu, 01 May 2014,
Ａｅｓｔｈｅｔｉｃ @ Thu, 29 Mar 2018,
No, Sam! @ Thu, 29 Mar 2018
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86. Cuboid route
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87. Prime power triples
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Oiler @ Thu, 30 Jan 2014,
0^0 @ Thu, 25 May 2017
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88. Product-sum numbers
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89. Roman numerals
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🍝🍝🍝 @ Wed, 28 Sep 2016
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90. Cube digit pairs
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Madelines @ Thu, 12 Oct 2017
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91. Right triangles with integer coordinates
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92. Square digit chains
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Kepler @ Thu, 30 May 2013,
We Hate Primes @ Thu, 27 Mar 2014,
Lone Prime @ Thu, 15 Jun 2017,
AwesomeSauceChicken @ Thu, 25 Sep 2014,
AtomicAwesomePants @ Thu, 25 Sep 2014
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93. Arithmetic expressions
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94. Almost equilateral triangles
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95. Amicable chains
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Lone Prime @ Thu, 15 Jun 2017
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96. Su Doku
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97. Large non-Mersenne prime
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Squirrels @ Thu, 02 Apr 2015,
Angry Armadillos @ Fri, 30 Jan 2015,
Fabulous Five @ Thu, 27 Jul 2017,
Kepler @ Thu, 30 May 2013,
The Triad @ Thu, 17 Aug 2017,
Username @ Thu, 30 May 2013,
Secret 🐿 @ Thu, 12 Oct 2017,
AwesomeSauceChicken @ Thu, 25 Sep 2014,
Fünke @ Thu, 30 May 2013
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98. Anagramic squares
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The Redshirts @ Thu, 30 Oct 2014
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99. Largest exponential
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No, Sam! @ Thu, 29 Mar 2018
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100. Arranged probability
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101. Optimum polynomial
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102. Triangle containment
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CII @ Thu, 30 Mar 2017,
Team 1 @ Thu, 16 Nov 2017
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103. Special subset sums: optimum
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104. Pandigital Fibonacci ends
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Good Democracy @ Thu, 26 Oct 2017
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105. Special subset sums: testing
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106. Special subset sums: meta-testing
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107. Minimal network
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108. Diophantine reciprocals I
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109. Darts
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110. Diophantine reciprocals II
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111. Primes with runs
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112. Bouncy numbers
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Better Than Clojure @ Thu, 29 Oct 2015,
Team Danny @ Thu, 28 Aug 2014,
AwesomeSauceChicken @ Thu, 25 Sep 2014,
Three Minutes @ Thu, 27 Apr 2017,
Secret 🐿 @ Thu, 11 May 2017,
99 Problems @ Mon, 29 Apr 2013,
Angry Armadillos @ Fri, 30 Jan 2015,
Infinite Sadness @ Thu, 30 Apr 2015,
HashBit @ Thu, 31 Mar 2016
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113. Non-bouncy numbers
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114. Counting block combinations I
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Just Add One! @ Thu, 01 Sep 2016
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115. Counting block combinations II
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116. Red, green or blue tiles
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117. Red, green, and blue tiles
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118. Pandigital prime sets
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119. Digit power sum
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120. Square remainders
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ℚ² @ Thu, 29 Jun 2017,
Good Democracy @ Thu, 26 Oct 2017,
max(pow(e,r)) @ Thu, 28 Aug 2014,
No @ Thu, 25 May 2017
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121. Disc game prize fund
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122. Efficient exponentiation
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123. Prime square remainders
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124. Ordered radicals
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125. Palindromic sums
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Team Beer @ Thu, 28 Aug 2014
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126. Cuboid layers
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127. abc-hits
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128. Hexagonal tile differences
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129. Repunit divisibility
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130. Composites with prime repunit property
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131. Prime cube partnership
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132. Large repunit factors
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133. Repunit nonfactors
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134. Prime pair connection
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135. Same differences
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136. Singleton difference
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137. Fibonacci golden nuggets
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138. Special isosceles triangles
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139. Pythagorean tiles
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140. Modified Fibonacci golden nuggets
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141. Investigating progressive numbers, n, which are also square.
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142. Perfect Square Collection
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143. Investigating the Torricelli point of a triangle
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144. Investigating multiple reflections of a laser beam.
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Ａｅｓｔｈｅｔｉｃ @ Thu, 29 Mar 2018
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145. How many reversible numbers are there below one-billion?
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Codew @ Thu, 27 Jul 2017,
Diophantine @ Thu, 14 Sep 2017
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146. Investigating a Prime Pattern
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147. Rectangles in cross-hatched grids
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148. Exploring Pascal's triangle.
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Sierpiński’s 🧀 @ Thu, 26 Jan 2017
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149. Searching for a maximum-sum subsequence.
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150. Searching a triangular array for a sub-triangle having minimum-sum.
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151. Paper sheets of standard sizes: an expected-value problem.
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152. Writing 1/2 as a sum of inverse squares
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153. Investigating Gaussian Integers
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154. Exploring Pascal's pyramid.
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155. Counting Capacitor Circuits.
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156. Counting Digits
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157. Solving the diophantine equation 1/a+1/b= p/10n
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158. Exploring strings for which only one character comes lexicographically after its neighbour to the left.
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👨💻 @ Thu, 23 Feb 2017
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159. Digital root sums of factorisations.
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160. Factorial trailing digits
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161. Triominoes
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162. Hexadecimal numbers
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163. Cross-hatched triangles
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164. Numbers for which no three consecutive digits have a sum greater than a given value.
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165. Intersections
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166. Criss Cross
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167. Investigating Ulam sequences
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168. Number Rotations
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169. Exploring the number of different ways a number can be expressed as a sum of powers of 2.
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Teamshawarma @ Thu, 26 Oct 2017,
EOF TABLE @ Thu, 28 Dec 2017
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170. Find the largest 0 to 9 pandigital that can be formed by concatenating products.
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171. Finding numbers for which the sum of the squares of the digits is a square.
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172. Investigating numbers with few repeated digits.
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173. Using up to one million tiles how many different 'hollow' square laminae can be formed?
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Pier Revue @ Thu, 27 Apr 2017,
The Hardware Problems @ Thu, 17 Aug 2017
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174. Counting the number of 'hollow' square laminae that can form one, two, three, ... distinct arrangements.
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175. Fractions involving the number of different ways a number can be expressed as a sum of powers of 2.
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176. Right-angled triangles that share a cathetus.
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177. Integer angled Quadrilaterals.
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178. Step Numbers
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179. Consecutive positive divisors
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MAD @ Fri, 26 Feb 2016,
Prime Triplets @ Thu, 11 May 2017,
The Hardware Problems @ Thu, 17 Aug 2017
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180. Rational zeros of a function of three variables.
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181. Investigating in how many ways objects of two different colours can be grouped.
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182. RSA encryption
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183. Maximum product of parts
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184. Triangles containing the origin.
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185. Number Mind
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186. Connectedness of a network.
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187. Semiprimes
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Good Democracy @ Thu, 26 Oct 2017,
Cauliflower @ Thu, 28 Jul 2016,
Team Fast @ Thu, 31 May 2018
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188. The hyperexponentiation of a number
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189. Tri-colouring a triangular grid
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190. Maximising a weighted product
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191. Prize Strings
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Young Diagram @ Thu, 28 Jan 2016
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192. Best Approximations
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193. Squarefree Numbers
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MICKEY🐭 @ Thu, 26 Apr 2018
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194. Coloured Configurations
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195. Inscribed circles of triangles with one angle of 60 degrees
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196. Prime triplets
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197. Investigating the behaviour of a recursively defined sequence
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198. Ambiguous Numbers
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199. Iterative Circle Packing
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200. Find the 200th prime-proof sqube containing the contiguous sub-string '200'
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201. Subsets with a unique sum
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202. Laserbeam
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No-eyed Dear @ Thu, 12 Oct 2017
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203. Squarefree Binomial Coefficients
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204. Generalised Hamming Numbers
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205. Dice Game
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Team 🐍 @ Thu, 27 Oct 2016,
Awesome @ Thu, 02 Apr 2015,
Programmers Just Want To Have Fun @ Thu, 30 Apr 2015,
AbstractSolutionFactorie @ Thu, 26 May 2016,
Team Fast @ Thu, 31 May 2018,
Icosahedral Cats @ Thu, 28 Sep 2017,
I don't know, dude. @ Thu, 30 Nov 2017
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206. Concealed Square
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AwesomeSauceChicken @ Thu, 25 Sep 2014,
Sierpiński’s 🧀 @ Thu, 27 Jul 2017,
Squirrels @ Thu, 02 Apr 2015,
AtomicAwesomePants @ Thu, 25 Sep 2014,
DynamicDuo @ Wed, 19 Nov 2014,
Team Beer @ Thu, 28 Aug 2014,
Team Fast @ Thu, 31 May 2018,
Awesome @ Thu, 02 Apr 2015,
Angry Armadillos @ Fri, 30 Jan 2015
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207. Integer partition equations
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208. Robot Walks
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209. Circular Logic
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210. Obtuse Angled Triangles
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211. Divisor Square Sum
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212. Combined Volume of Cuboids
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213. Flea Circus
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214. Totient Chains
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215. Crack-free Walls
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216. Investigating the primality of numbers of the form 2n2-1
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217. Balanced Numbers
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218. Perfect right-angled triangles
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219. Skew-cost coding
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220. Heighway Dragon
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221. Alexandrian Integers
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222. Sphere Packing
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223. Almost right-angled triangles I
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224. Almost right-angled triangles II
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225. Tribonacci non-divisors
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226. A Scoop of Blancmange
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227. The Chase
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228. Minkowski Sums
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229. Four Representations using Squares
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230. Fibonacci Words
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231. The prime factorisation of binomial coefficients
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232. The Race
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233. Lattice points on a circle
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234. Semidivisible numbers
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235. An Arithmetic Geometric sequence
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236. Luxury Hampers
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237. Tours on a 4 x n playing board
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238. Infinite string tour
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239. Twenty-two Foolish Primes
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240. Top Dice
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241. Perfection Quotients
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242. Odd Triplets
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243. Resilience
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Pier Revue @ Thu, 27 Apr 2017
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244. Sliders
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245. Coresilience
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246. Tangents to an ellipse
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247. Squares under a hyperbola
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248. Numbers for which Euler’s totient function equals 13!
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249. Prime Subset Sums
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250. 250250
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251. Cardano Triplets
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252. Convex Holes
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253. Tidying up
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254. Sums of Digit Factorials
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255. Rounded Square Roots
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256. Tatami-Free Rooms
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257. Angular Bisectors
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258. A lagged Fibonacci sequence
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259. Reachable Numbers
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260. Stone Game
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261. Pivotal Square Sums
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262. Mountain Range.
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263. An engineers' dream come true
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264. Triangle Centres
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265. Binary Circles
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266. Pseudo Square Root
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267. Billionaire
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268. Counting numbers with at least four distinct prime factors less than 100
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269. Polynomials with at least one integer root
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270. Cutting Squares
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271. Modular Cubes, part 1
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272. Modular Cubes, part 2
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273. Sum of Squares
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274. Divisibility Multipliers
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275. Balanced Sculptures
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276. Primitive Triangles
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277. A Modified Collatz sequence
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278. Linear Combinations of Semiprimes
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279. Triangles with integral sides and an integral angle
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280. Ant and seeds
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281. Pizza Toppings
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282. The Ackermann function
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283. Integer sided triangles for which the area/perimeter ratio is integral.
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284. Steady Squares
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285. Pythagorean odds
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286. Scoring probabilities
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287. Quadtree encoding (a simple compression algorithm)
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288. An enormous factorial
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289. Eulerian Cycles
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290. Digital Signature
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291. Panaitopol Primes
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292. Pythagorean Polygons
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293. Pseudo-Fortunate Numbers
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294. Sum of digits - experience #23
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295. Lenticular holes
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296. Angular Bisector and Tangent
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297. Zeckendorf Representation
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298. Selective Amnesia
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299. Three similar triangles
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300. Protein folding
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301. Nim
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Easily Distracted @ Thu, 28 Sep 2017,
Young Diagram @ Thu, 28 Jan 2016
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302. Strong Achilles Numbers
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303. Multiples with small digits
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304. Primonacci
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305. Reflexive Position
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306. Paper-strip Game
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307. Chip Defects
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308. An amazing Prime-generating Automaton
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309. Integer Ladders
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310. Nim Square
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311. Biclinic Integral Quadrilaterals
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312. Cyclic paths on Sierpiński graphs
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313. Sliding game
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314. The Mouse on the Moon
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315. Digital root clocks
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316. Numbers in decimal expansions
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317. Firecracker
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318. 2011 nines
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319. Bounded Sequences
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320. Factorials divisible by a huge integer
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321. Swapping Counters
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322. Binomial coefficients divisible by 10
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323. Bitwise-OR operations on random integers
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Sierpiński’s 🧀 @ Thu, 27 Jul 2017,
Fabulous Five @ Thu, 27 Jul 2017
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324. Building a tower
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325. Stone Game II
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326. Modulo Summations
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327. Rooms of Doom
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328. Lowest-cost Search
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329. Prime Frog
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330. Euler's Number
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331. Cross flips
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332. Spherical triangles
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333. Special partitions
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334. Spilling the beans
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335. Gathering the beans
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336. Maximix Arrangements
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337. Totient Stairstep Sequences
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338. Cutting Rectangular Grid Paper
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339. Peredur fab Efrawg
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340. Crazy Function
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341. Golomb's self-describing sequence
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342. The totient of a square is a cube
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343. Fractional Sequences
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344. Silver dollar game
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345. Matrix Sum
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Coca-Cola® @ Thu, 25 May 2017
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346. Strong Repunits
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347. Largest integer divisible by two primes
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348. Sum of a square and a cube
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349. Langton's ant
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350. Constraining the least greatest and the greatest least
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351. Hexagonal orchards
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352. Blood tests
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353. Risky moon
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354. Distances in a bee's honeycomb
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355. Maximal coprime subset
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356. Largest roots of cubic polynomials
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|
357. Prime generating integers
|
No Ether @ Thurs, 26 Feb 2015
|
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358. Cyclic numbers
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359. Hilbert's New Hotel
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360. Scary Sphere
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361. Subsequence of Thue-Morse sequence
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362. Squarefree factors
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363. Bézier Curves
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364. Comfortable distance
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365. A huge binomial coefficient
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366. Stone Game III
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367. bozo sort
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368. A Kempner-like series
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369. Badugi
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370. Geometric triangles
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371. Licence plates
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372. Pencils of rays
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373. Circumscribed Circles
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374. Maximum Integer Partition Product
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375. Minimum of subsequences
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376. Nontransitive sets of dice
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|
377. Sum of digits, experience 13
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|
378. Triangle Triples
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|
379. Least common multiple count
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|
380. Amazing Mazes!
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381. (prime-k) factorial
|
Deer F. Kennedy @ Thu, 30 Nov 2017
|
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382. Generating polygons
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383. Divisibility comparison between factorials
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384. Rudin-Shapiro sequence
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385. Ellipses inside triangles
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386. Maximum length of an antichain
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|
387. Harshad Numbers
|
The PinPals @ Thu, 25 Jun 2015
|
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388. Distinct Lines
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389. Platonic Dice
|
The Hardware Problems @ Thu, 17 Aug 2017
|
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390. Triangles with non rational sides and integral area
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391. Hopping Game
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392. Enmeshed unit circle
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393. Migrating ants
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394. Eating pie
|
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395. Pythagorean tree
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396. Weak Goodstein sequence
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397. Triangle on parabola
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398. Cutting rope
|
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399. Squarefree Fibonacci Numbers
|
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400. Fibonacci tree game
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401. Sum of squares of divisors
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402. Integer-valued polynomials
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403. Lattice points enclosed by parabola and line
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404. Crisscross Ellipses
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405. A rectangular tiling
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406. Guessing Game
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407. Idempotents
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408. Admissible paths through a grid
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409. Nim Extreme
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410. Circle and tangent line
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411. Uphill paths
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412. Gnomon numbering
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413. One-child Numbers
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414. Kaprekar constant
|
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415. Titanic sets
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416. A frog's trip
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417. Reciprocal cycles II
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418. Factorisation triples
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419. Look and say sequence
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420. 2x2 positive integer matrix
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421. Prime factors of n15+1
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422. Sequence of points on a hyperbola
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423. Consecutive die throws
|
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424. Kakuro
|
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425. Prime connection
|
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426. Box-ball system
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427. n-sequences
|
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428. Necklace of circles
|
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