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) {
        Scanner in = new Scanner(System.in);
        long k = in.nextLong();
        long sum=0;
        long temp=k;
        for(long i=0;i<k;i++){
            if(k==i+1){
                k=k+i*i;
                for(long j=0;j<temp;j++){
                  sum=sum+(k);
                   
                   k=k+2;
                }
                break;
            }
        }
       System.out.println(sum);
        in.close();
    }
}