The positive integers, x, y, and z, are consecutive terms of an arithmetic progression. Given that n is a positive integer, the equation, x2y2
z2 = n, has exactly one solution when n = 20:
132 102
72 = 20
In fact there are twenty-five values of n below one hundred for which the equation has a unique solution.
How many values of n less than fifty million have exactly one solution?
These problems are part of Project Euler and are licensed under CC BY-NC-SA 2.0 UK