View Code of Problem 71

#include<stdio.h>

int main()
{
	int i,n;
	double t,sum;
	double x=2,y=1;
	scanf("%d", &n);
	for( i=1; i<=n; i++ )
	{
		sum += x/y;
		t = y;
		y = x;
		x = x + t;
	}
	printf("%.6lf", sum);
	return 0;
}