#include <stdio.h>

int main() {

    int n = 0;//输入整数
    scanf("%d", &n);
    int i = 0;//遍历
    int sum = 0;
    for (i = 1; i <= n; i++)
    {   int j = 0;
        int t= 0 ;
        for (j = 1; j<=i;j++)
        {
            t += j;
        }
        sum += t;
    }
    printf("%d\n", sum);

    return 0;
}