백준 17427 java

import java.util.Scanner;

public class bj17427 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int N, i;
        long sum = 0;

        N = scanner.nextInt();
        /*
        N = 1일 때 : 1(1) :
        N = 2일 때 : 1(1) / 2(1, 2) : 1 + 1 + 2 = 4
        N = 3일 때 : 1(1) / 2(1, 2) / 3(1, 3) : 1 + 1 + 2 + 1 + 3 = 8
        N = 4일 떄 : 1(1) / 2(1, 2) / 3(1, 3) / 4(1, 2, 4) : 1 + 1 + 2 + 1 + 3 + 1 + 2 + 4 = 15
        ....
         */
        for(i = 1; i <= N; i++)
        {
            sum += (i * (N / i));
        }
        System.out.println(sum);

        scanner.close();
    }
}