#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

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