#include "iostream"

using namespace std;

long long sum = 0 , n , h = 0;

int main() {
    cin >> n;

    for (int i = 1 ; i <= n ; i++) {
        sum += (1 + i ) * i / 2;//开个挂，高斯公式
    }

    cout << sum << endl;
    return 0;
}