#include<stdio.h>
int main()
{
int i;
double a, b, c,e;
a = 2;
b = 1;
c = 0;
e = 0;
for (i = 1; i <= 20;i++)
{
e = e + a / b; //累加和
c = a; //把被除数拿出来在下面替换成除数
a = a + b; //根据规律可得下一项被除数等于上一项的被除数加除数
b = c; //除数换成上面取出的被除数
}
printf("%f", e);
return 0;
}
原文:https://www.cnblogs.com/old-horse/p/12498035.html