学习了

6楼的函数调用错了，    Num += jiecheng(n);应该改为    Num += jiecheng(i+1);

嗯，挺不错的！！
能不能给简单点啊！？

            int s=0 ;
            int a=1;
            for (int b = 1; b <= 5; b++)
            {
                a *= b;
                s += a;
            }
            Console.WriteLine(s);
            Console.ReadLine();