import java.util.Scanner;
public class SumSeries
{
        public static void main()
        {
                int n=0,i=0;
                long sum=0,num=0;
                Scanner sc=new Scanner(System.in);
                System.out.println("ENTER THE Nth TERM");
                n=sc.nextInt();
                for(i=1;i<=n;i++)
                {
                        num=num+2;
                        sum=sum+num; 
                }
                System.out.println("SUM OF SERIES="+sum);
        }
}