#include <stdio.h>

int main() {
    int n = 0;
    int i = 0;
    int sum = 0;
    int Sum_part = 0;
    scanf("%d",&n);
    for (i = 1; i <= n; i++) {
        Sum_part += i;
        sum += Sum_part;
    }
    printf("%d",sum);
    return 0;
}