题解 | #等差数列#

递归求出第n个数组， An = An-1 + 3, A0 =2;没啥技巧。

import java.util.Scanner;

public class Main {

    public static void main(String[] arg) {
        Scanner scan = new Scanner(System.in);

        while (scan.hasNextInt()) {
            int n = scan.nextInt();
            int[] inputArr = new int[n];
            for (int i = 0; i < n; i++) {
                inputArr[i] = getItem(i);
            }
            int total = 0;
            for (int i = 0; i < inputArr.length; i++) {
                total +=inputArr[i];
            }
            System.out.println(total);
        }

    }

    public static int getItem(int i){
        if(i==0){
            return 2;
        }else {
            return getItem(i - 1) + 3;
        }
    }

}