float Column(int length);
int main(int argc, char* argv[])
{
int length;
scanf("%d",&length);
float sum= Column(length);
printf("%f\n",sum);
return 0;
}
float Column(int length)
{
// 分子 分母
int numerator=2,denominator=1;
float sum=0;
for(int i=0;i {
int tmp=numerator;
sum+=(numerator/(denominator*1.0F));
numerator+=denominator;
denominator=tmp;
}
return sum;
}
