#include<bits/stdc++.h>
using namespace std;
typedef long double ld;
const int M=1e6;
ld s[M+10];
ld qry(int x)
{
	if(x<=M) return s[x];
	else return (x+0.5)*log(x)-x+0.92;
}
ld calc(int n,int k)
{
	k=min(k,n*2/3);
	return qry(n)-qry(k)-qry(n-k)+log(2)*k;
}
int T,n,k;
int main()
{
	for(int i=2;i<=M;i++) s[i]=s[i-1]+log(i);
	scanf("%d",&T);
	while(T--)
	{
		scanf("%d%d",&n,&k);
		printf("%.10Lf\n",n*log(3)+log(3ll*k+1)-calc(n,k));
	}
}