#include <bits/stdc++.h>

using namespace std;

unsigned long long sumOfGroup(unsigned long long k) {
    // Return the sum of the elements of the k'th group.
    
    unsigned long long sum=0;
    for (unsigned long long i=0; i<k; i++)
        sum+= (k*k)-(k-1) + 2*i;
    return sum;
}

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