#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) {
    #define ll long long
    ll kk = k;
    ll p = kk * (kk - 1) + 1;
    ll q = kk * (kk + 1) - 1;
    return (p + q) * k / 2;
}

int main() {
    int k;
    cin >> k;
    long answer = sumOfGroup(k);
    cout << answer << endl;
    return 0;
}