迭代法 丢羊了

static void Main(string[] args)
        {
            int y = 2;                                   //过一个村庄丢一半零一只，过了7个村庄还是2只，求原来几只
            for (int i = 1; i <=7; i++)
            {
                y = (y + 1) * 2;
            }
            Console.WriteLine(y);
            Console.ReadLine();
        }