编程：有一个分数序列：2/1, 3/2, 5/3, 8/5, 13/8, 21/13, 求出这个序列的前20项之和。c语言

#include <stdio.h>

int main() {
double a = 2, b = 1, sum = 0, temp;
int i;
for (i = 1; i <= 20; i++) {
sum += a / b;
temp = b;
b = a;
a = a + temp;
}
printf("前20项之和为 %lf\n", sum);
return 0;
}