求1到任意整数的阶乘之和 例如(1!+2!+3!+~~~+n!)

using System;
using System.Collections.Generic;
using System.Text;

namespace Text
{
class Program
{
static void Main(string[] args)
{
Program p = new Program();
Console .WriteLine (p.GetSum(3));
}
private int GetSum(int x)
{

int sum = 0;
for (int i = 1; i <= x; i++)
{
int t = 1;
for (int j = 1; j <= i; j++)
{
t = t * j;
}
sum += t;
}
return sum;
}
}

}