#include <bits/stdc++.h>

using namespace std;

long sumOfGroup(int k) 
{
	unsigned long long t, sum = 0, trailer = 1;
	
	for( int i = 1; i <= k; i += 1)
	{
		t = i;
		while ( t-- )
		{
			if( i != k )
			{			
				trailer += i*2;
				break;
			}
			sum += trailer ;
			trailer += 2;
		}
	}
	return sum;
}

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