1 2 3 4 0
1.00 3.00 5.67 8.83
#include<stdio.h>
double f[50001]={0,1.00};
int main()
{
int n,i,j;
double s=1.0;
for(i=2;i<50001;i++)
{
s+=2.0*(1.0/i);
f[i]=f[i-1]+s;
}
while(scanf("%d",&n)==1,n)
printf("%.2lf\n",f[n]);
return 0;
}原文：http://blog.csdn.net/darwin_/article/details/18911811