C语言求Sn=1!+2!+3!+4!+5!+…+n!之和

#include<stdio.h>int main(){    int i, n;    __int64 sum = 0, f = 1;    scanf("%d", &n);    for(i = 1; i <= n; i++)    {        f *= i;        sum += f;    }    printf("%lld\n",sum);    return 0;}

或者，类型使用long int

#include<stdio.h>int main(){    int i, n;    long int sum = 0, f = 1;    scanf("%d", &n);    for(i = 1; i <= n; i++)    {        f *= i;        sum += f;    }    printf("%d\n",sum);    return 0;}