# Problem 565: Divisibility of sum of divisors Let \$\\sigma(n)\$ be the sum of the divisors of \$n\$. E.g. the divisors of 4 are 1, 2 and 4, so \$\\sigma(4)=7\$. The numbers \$n\$ not exceeding 20 such that 7 divides \$\\sigma(n)\$ are: 4,12,13 and 20, the sum of these numbers being 49. Let \$S(n , d)\$ be the sum of the numbers \$i\$ not exceeding \$n\$ such that \$d\$ divides \$\\sigma(i)\$. So \$S(20 , 7)=49\$. You are given: \$S(10\^6,2017)=150850429\$ and \$S(10\^9 , 2017)=249652238344557\$. Find \$S(10\^{11} , 2017)\$