function to find prime divisors of all numbers from 1 to n
function Sum ( N ) { let SumOfPrimeDivisors = new Array ( N + 1 ) ; for ( let i = 0 ; i < SumOfPrimeDivisors . length ; i ++ ) { SumOfPrimeDivisors [ i ] = 0 ; } for ( let i = 2 ; i <= N ; ++ i ) {