import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) throws IOException
    {
        Scanner in = new Scanner(System.in);

        //long time = System.currentTimeMillis();

        long k = in.nextInt();

        long res = k * (k - 1) * k + k * (k + 1) - k;

        System.out.println(res);


        //System.out.println(System.currentTimeMillis() - time);
    }
}