分數序列 前20項之和

#include <stdio.h>
//分數序列
int main()
{
	int  i;
	double m = 1.0, n = 2.0, a,b;
	a = n / m;
	for (i = 1; i <20; i++)
	{
		b = m + n;
		m = n;
		n = b;
		a = a + n / m;
	}
	printf("%lf", a);
	return 0;
}