Problem 130 of Project Euler is a continuation of problem 129, so if you have already solved that this one should be pretty easy. It reads

**Find the sum of the first twenty-five composite values of n for which GCD(n, 10) = 1 and n – 1 is divisible by A(n).**

If you have already solved Problem 129 as we have, this one can be solved pretty easily. We already have a function that will give us A(n), so we can just brute force our way through the problem calculating check if n-1 is divisible by A(n) and n is not a prime.

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Project Euler