The summation of number of divisors of the divisors of n...
https://codeforces.com/group/H10hR2t6Sj/contest/338701/problem/J Let M be a positive integer. Let f(M) be the number of positive divisors of an integer M. For example f(12)=6 and they are 1,2,3,4,6,12. Let g(M)