#include<iostream>
using namespace std;
void main()
{
    int A(int n);//递归求阶乘
    cout << "请输入N值:";
    int i, N, sum = 0;
    cin >> N;
    if (N > 0)
    {
        for (i = N; i >= 1; i--)
        {
            sum += A(i);
        }
        cout << "结果：" << sum << endl;
    }
    else
        cout << "N必须为正整数！\n";
    system("pause");
}
int A(int n)
{
    if (n > 1)
        return A(n - 1)*n;
    if (n == 1)
        return 1;
}