#include <iostream>

using namespace std;

int main()
{
    int n;
    long long sum = 0;
    cin >> n;
    for (int i = 0; i <= n; i++)
    {
        sum += i * (i + 1) + ((i + 1) * i) / 2;
    }
    cout << sum << endl;
    return 0;
}