计算分数序列前n项和c语言代码

下面是计算分数序列前n项和的C语言代码：

#include <stdio.h>

int main() {
    int n;
    double sum = 2.0, a = 2.0, b = 1.0, c;
    scanf("%d", &n);
    for (int i = 2; i <= n; i++) {
        c = a + b;
        sum += c / b;
        b = a;
        a = c;
    }
    printf("%.2f", sum);
    return 0;
}