package q5xx;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class Q580_2 {
	InputStream is;
	PrintWriter out;
	String INPUT = "";
	
	void solve()
	{
		for(int T = ni();T >= 1;T--){
			int n = ni();
			long[] ps = new long[n];
			for(int i = 0;i < n;i++)ps[i] = nl();
			long[] qs = new long[n];
			int[] hs = new int[n];
			for(int i = 0;i < n;i++){
				qs[i] = ps[i]-1;
				while(qs[i] % 2 == 0){
					qs[i] /= 2;
					hs[i]++;
				}
			}
			
			double[] E = new double[1<<n];
			for(int i = 1;i < 1<<n;i++){
				if(Integer.bitCount(i) == 1){
					E[i] = 1;
				}else{
					double xt = 1;
					double m = 1;
					int[] lh = new int[64];
					for(int j = 0;j < n;j++){
						if(i<<~j<0){
							xt = xt * qs[j];
							m = m * ps[j];
							lh[hs[j]]++;
						}
					}
					double[] vh = new double[64];
					double last = 0;
					for(int j = 63;j >= 0;j--){
						if(lh[j] == 0)continue;
						int[] es = new int[j+1];
						es[1] = Integer.bitCount(i);
						for(int k = 0;k < j-1;k++){
							es[k+1] -= lh[k];
						}
						for(int k = 1;k < j;k++){
							es[k] += es[k-1];
						}
						for(int k = 1;k < j;k++){
							es[k] += es[k-1];
						}
						for(int k = 1;k < j;k++){
							vh[j] += Math.pow(2, es[k]);
						}
						vh[j]++;
						vh[j] *= xt;
						last = vh[j];
					}
					double e = 0;
					double p = 0;
					double[] w = new double[1<<n];
					for(int j = i-1&i;j > 0;j=j-1&i){ 
						int rem = 99;
						for(int k = 0;k < n;k++){
							if((i^j)<<~k<0){
								rem = Math.min(rem, hs[k]);
							}
						}
						e += (E[j] + E[i^j]) * vh[rem] / m;
						p += vh[rem] / m;
						
						double lm = 1;
						for(int k = 0;k < n;k++){
							if(j<<~k<0){
								lm = lm * ps[k];
							}
						}
						w[j] = (m/lm-1)/m;
						
//						double le = E[j] + E[i^j];
//						p += (m/lm-1)/m;
//						for(int k = j-1&j;k > 0;k=k-1&j){
//							le -= (E[k] + E[i^k]);
//							p -= (m/lm-1)/m;
//						}
//						e += le * ((m/lm-1)/m);
					} // not include j=0
					for(int k = 0;k < n;k++){
						if(i<<~k<0){
							int ii = i^1<<k;
							for(int j = ii;j > 0;j=j-1&ii){ 
								w[j] -= w[j|1<<k];
							}
						}
					}
					for(int j = i-1&i;j > 0;j=j-1&i){ 
						e += (E[j] + E[i^j])*w[j];
						p += w[j];
					} // not include j=0
					
					p += (xt+last+1)/m;
					E[i] = (e+1) / (1. - (xt+last+1)/m);
//					tr(i, e);
				}
			}
			out.printf("%.9f\n", E[(1<<n)-1]);
		}
	}
	
	public static void trnz(int[] o)
	{
		for(int i = 0;i < o.length;i++)if(o[i] != 0)System.out.print(i+":"+o[i]+" ");
		System.out.println();
	}

	
	public static long pow(long a, long n, long mod) {
		//		a %= mod;
		long ret = 1;
		int x = 63 - Long.numberOfLeadingZeros(n);
		for (; x >= 0; x--) {
			ret = ret * ret % mod;
			if (n << 63 - x < 0)
				ret = ret * a % mod;
		}
		return ret;
	}
	
	public static long gcd(long a, long b) {
		while (b > 0) {
			long c = a;
			a = b;
			b = c % b;
		}
		return a;
	}
	
	
	void run() throws Exception
	{
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		long s = System.currentTimeMillis();
		solve();
		out.flush();
		if(!INPUT.isEmpty())tr(System.currentTimeMillis()-s+"ms");
	}
	
	public static void main(String[] args) throws Exception { new Q580_2().run(); }
	
	private byte[] inbuf = new byte[1024];
	private int lenbuf = 0, ptrbuf = 0;
	
	private int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private double nd() { return Double.parseDouble(ns()); }
	private char nc() { return (char)skip(); }
	
	private String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private char[][] nm(int n, int m)
	{
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { System.out.println(Arrays.deepToString(o)); }
}