求阶乘及其和

 int sum = 0;
            Console.Write("请输入数字：");
            int shu = int.Parse(Console.ReadLine());
            for (int i = 1; i <= shu; i++)//从1开始遍历
            {
                int jiecheng = 1;
                //求i的阶乘
                for (int j = 1; j <= i; j++)
                {
                    jiecheng = jiecheng*j;
                }
                sum = sum + jiecheng;//累加
            }

            Console.WriteLine("结果为：" + sum);