#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(long long k) {
    // Return the sum of the elements of the k'th group.
    long long num = k - 1;
    num = num * (num + 1);
    long long ans = k * num + k * k;
    return ans;
}

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