Problem #239
Divisor Count
The function d(n) denotes the number of positive divisors of an integer n. For example, d(6) = 4, because there are 4 divisors of 6 and they are 1, 2, 3, and 6.
We create a function f(n) which denotes “The summation of the number of divisors of the divisors” of an integer n.
For example, f(6) = d(1) + d(2) + d(3) + d(6) = 1 + 2 + 2 + 4= 9.
Find \displaystyle \sum_{i=1}^{2019} f(i!) mod 10^9+7, where n! means factorial of n.