C :

#include <stdio.h>
int main()
{
	int n;
	while(~scanf("%d", &n))
		printf("%d\n", 2*n*n-n+1);
	return 0;
}

C++ :

#include <iostream>
using namespace std;
int main(){
	int a[10001];
	a[1] = 2;
	for(int i=2;i<10001;i++)
		a[i] = a[i-1]+(i-1)*4+1;
	for(int n;cin>>n;)
		cout<<a[n]<<endl;
	return 0;
}

Java :

 import java.util.*;
 public class Main{
     public static void main(String[] args){
         Scanner in = new Scanner(System.in);
         while(in.hasNext()){
            int N = in.nextInt();
            int sum = 0;
            int n =(int) Math.pow(N,2);
             sum = 2 * n - N + 1;
             System.out.println(sum);
            }
        }
    }