Euler in Babylon

Sum of sum of divisors

October 06, 2013

Let d(k) be the sum of all divisors of k. We define the function S(N) = $\sum_{i=1}^N \sum_{j=1}^Nd(i \cdot j)$. For example, S(3) = d(1) + d(2) + d(3) + d(2) + d(4) + d(6) + d(3) + d(6) + d(9) = 59.

You are given that S(103) = 563576517282 and S(105) mod 109 = 215766508. Find S(1011) mod 109.


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