#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

ll sumOfGroup(ll k) {
    ll n = k*k - k + 1;
    ll ans = k*(n + k-1);
    return ans;
}

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