#include <bits/stdc++.h>
using namespace std;
inline int read(int x=0,bool f=1){
	char c=getchar();
	while(c>'9'||c<'0'){if(c=='-')f=0;c=getchar();}
	while(c>='0'&&c<='9'){x=(x<<3)+(x<<1)+c-'0';c=getchar();}
	return f?x:-x;
}
int n,t;
long double ans=1;
int main(){
    t=read();
    while(t--){
    	n=read()>>1;
    	for(int i=1;i<n;i++)
        	ans=ans*(i+n-1)/(i<<2);
		printf("%.4Lf",1-ans);
		putchar(10);
		ans=1;
	}
    return 0;
}