405 遞迴函數

import java.util.Scanner;
public class JPA405 {
    static Scanner keyboard = new Scanner(System.in);
    public static void main(String args[]) {

int n;
System.out.print("Input the number n :");
n= keyboard.nextInt();
System.out.println("Ans :　"+sum2(n));
   }

    static int sum2(int n) {
if(n>1){
return sum2(n-1)+2*n;
}
else{
return 2;
}
      }
}