Sum of product of all integers upto N with their count of divisors | Java program for the above approach ; Function to find the sum of the product of all the integers and their positive divisors up to N ; Iterate for every number between 1 and N ; Find the first multiple of i between 1 and N ; Find the last multiple of i between 1 and N ; Find the total count of multiple of in [ 1 , N ] ; Compute the contribution of i using the formula ; Add the contribution of i to the answer ; Return the result ; Driver code ; Given N ; function call
class GFG { static int sumOfFactors ( int N ) { int ans = 0 ; for ( int i = 1 ; i <= N ; i ++ ) { int first = i ; int last = ( N / i ) * i ; int factors = ( last - first ) / i + 1 ; int totalContribution = ( ( ( factors ) * ( factors + 1 ) ) / 2 ) * i ; ans += totalContribution ; } return ans ; } public static void main ( String [ ] args ) { int N = 3 ; System . out . println ( sumOfFactors ( N ) ) ; } }