Sum of all divisors from 1 to n. Given a positive integer N., The task is to find the value of Σi from 1 to N F(i) where function F(i) for the number i is defined as the sum of all divisors of i.

Function ‘sumOfDivisors(n)’ is defined as the sum of all divisors of ‘n’. Find the sum of ‘sumOfDivisors(i)’ for all ‘i’ from 1 to ‘n’. Therefore our answer is sumOfDivisors(1) + sumOfDivisors(2) + ...

A recursive scheme for determination of the sum-of-divisors function is presented. As all of the formulas involve triangular numbers, the scheme is therefore compared for efficiency with another known ...