#include<bits/stdc++.h>
using namespace std;
int main () {
	long long n,sum = 0;
	cin >> n;
	for (int i = 1;i <= n; i++) {
		for (int j = 1;j <= i; j++) {
			sum = sum + j;
		}
	}
	cout <<sum ;
	return 0;
}