정보처리산업기사 자바 재귀함수 기출문제

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        int i;
        Scanner sc = new Scanner(System.in);
        System.out.print("숫자를 입력하시오: "); // 입력 5
        i = sc.nextInt();
        recursive(i);
        sc.close();
    }

    static int recursive(int n) {
        int i;
        if (n < 1)
            return 2;
        else {
            i = (2 * recursive(n - 1)) + 1;
            System.out.println(i);
            return i;
        }
    }

    /**
     * (2 * recur(4) + 1) => 2 * 47 + 1 = 95
     * (2 * recur(3) + 1) => 2 * 23 + 1 = 47
     * (2 * recur(2) + 1) => 2 * 11 + 1 = 23
     * (2 * recur(1) + 1) => 2 * 5 + 1 = 11
     * (2 * recur(0) + 1) => 2 * 2 + 1 = 5
     *
     * 출력
     *
     * 5
     * 11
     * 23
     * 47
     * 95
     */
}