【c语言】有一个分数序列 2/1+3/2+5/3+8/5+13/8+… 求出这个数列前20项的和

/*有一个分数序列2/1+3/2+5/3+8/5+13/8+…求出这个数列前20项的和*/#include <stdio.h>int main(){double i=1.0,j = 2.0,c,d;double sum = 0.0;for( d = 0; d < 20; d++){sum = sum + j/i;c=j;j=i+j;i=c;}printf("2/1+3/2+5/3+8/5+13/8+...前20项和为：%f\n",sum);return 0;}<img src="http://img.blog.csdn.net/20150326230235862?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhb3lhcWlhbjU1Mg==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />