#include <iostream>

using namespace std;

long sumOfGroup(long k) 
{
	// Return the sum of the elements of the k'th group.
	long step = k*(k - 1);

	return (k + step)*k;
}

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