Prime generating integers
Problem 357Published on Saturday, 5th November 2011, 04:00 pm; Solved by 3115; Difficulty rating: 10%
Consider the divisors of 30: 1,2,3,5,6,10,15,30.
It can be seen that for every divisor d of 30, d+30/d is prime.
Find the sum of all positive integers n not exceeding 100 000 000
such that for every divisor d of n, d+n/d is prime.