题解 | 牛牛学数列6

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int x = in.nextInt();
        int a = 0, b = 1, c = 1;
        int d = 0;
        for(int i = 0; i < x - 3 ; i++)
        {
            d = equation(a,b,c);
            a = b;
            b = c;
            c = d;
        }
        System.out.println(d);
    }
    public static int equation(int x, int y,int z)
    {
        return x + y * 2 + z;
    } 
}