TQC+ JAVA

JPA04.java

import java.util.Scanner;
public class JPA03 {
    static Scanner keyboard = new Scanner(System.in);
    public static void main(String[] args) {
		System.out.print("Input the number n: ");
		int num = keyboard.nextInt();
		System.out.println("Ans: " + sum2(num));
    }
	public static int sum2(int num) {
		if(num < 1) {
			return 0;
		}
		if(num == 1) {
			return 2;
		}
		return sum2(num - 1) + 2 * num;
	}
}