Problem 241
Perfection Quotients

For a positive integer n, let σ(n) be the sum of all divisors of n, so e.g. σ(6) = 1 + 2 + 3 + 6 = 12.

A perfect number, as you probably know, is a number with σ(n) = 2n.

Let us define the perfection quotient of a positive integer as p(n)
σ(n)

n
.

Find the sum of all positive integers n ≤ 1018 for which p(n) has the form k + 12, where k is an integer.

These problems are part of Project Euler and are licensed under CC BY-NC-SA 2.0 UK

http://projecteuler.net/problem=241