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#include <bits/stdc++.h>

using namespace std;
#define fors(u, n, s) for(int u = (s); u<(n); u++)
#define foru(u, n) fors(u, n, 0)
#define f first
#define s second
#define vec vector
#define pb push_back
#define sz(x) ((int)x.size())
typedef long long ll;

// #define debug(x) cerr << __LINE__ << " | " << x << endl
#define debug(x) {}

const int MOD = 1e9+7;
struct Modular {
  int value;
  static const int MOD_value = MOD;

  Modular(long long v = 0) { value = v % MOD; if (value < 0) value += MOD;}
  Modular(long long a, long long b) : value(0){ *this += a; *this /= b;}

  Modular& operator+=(Modular const& b) {value += b.value; if (value >= MOD) value -= MOD; return *this;}
  Modular& operator-=(Modular const& b) {value -= b.value; if (value < 0) value += MOD;return *this;}
  Modular& operator*=(Modular const& b) {value = (long long)value * b.value % MOD;return *this;}

  friend Modular mexp(Modular a, long long e) {
    Modular res = 1; while (e) { if (e&1) res *= a; a *= a; e >>= 1; }
    return res;
  }
  friend Modular inverse(Modular a) { return mexp(a, MOD - 2); }

  Modular& operator/=(Modular const& b) { return *this *= inverse(b); }
  friend Modular operator+(Modular a, Modular const b) { return a += b; }
  friend Modular operator-(Modular a, Modular const b) { return a -= b; }
  friend Modular operator-(Modular const a) { return 0 - a; }
  friend Modular operator*(Modular a, Modular const b) { return a *= b; }
  friend Modular operator/(Modular a, Modular const b) { return a /= b; }
  friend std::ostream& operator<<(std::ostream& os, Modular const& a) {return os << a.value;}
  friend bool operator==(Modular const& a, Modular const& b) {return a.value == b.value;}
  friend bool operator!=(Modular const& a, Modular const& b) {return a.value != b.value;}
};

const int N = 5e6;
Modular fac[N];
Modular twoexp[N];

Modular anachronic_help(int n, int swaps, int first_swap){
	int up_swaps = swaps>>1;
	int down_swaps = swaps - up_swaps;
	
	bool first_swap_down = swaps&1;
	
	int spaces;
	if(first_swap_down){
		spaces = n - up_swaps - first_swap - (first_swap&1);
	} else {
		spaces = n - down_swaps - first_swap + (first_swap&1);
	}
		
	int free = 2*n-swaps-1;
	
	return twoexp[swaps]*Modular(spaces)*fac[free];
}

Modular duble_help(int n, int swaps, int first_swap){
	int up_swaps = swaps>>1;
	int down_swaps = swaps - up_swaps;

	bool first_swap_down = swaps&1;

	int first_spaces;
	int second_spaces;
	
	if(first_swap_down) {
		first_spaces = first_swap + (first_swap&1);
		second_spaces = n - up_swaps - 1;
	} else {
		first_spaces = first_swap - (first_swap&1);
		second_spaces = n - down_swaps - 1;
	}

	int free = 2*n-swaps-2;

	return twoexp[swaps]*Modular(first_spaces)*Modular(second_spaces)*fac[free];
}

void solve() {
	int n; cin >> n; n *= 2;
	vec<int> v(n);
	foru(i, n) cin >> v[i];

	int zero_cnt = 0;
	int two_cnt = 0;
	for(auto i : v)
		zero_cnt += (i==0),
		two_cnt += (i==2);

	if(zero_cnt && two_cnt){
		cout << 0 << endl;
		return;
	}

	if(zero_cnt == 0 && two_cnt == 0){
		cout << Modular(2)*Modular(n)*Modular(n)*Modular(n-1)*fac[2*n-3]/mexp(Modular(2), n) << endl;
		return;
	}

	if(zero_cnt == n || two_cnt == n){
		cout << Modular(n/2)*Modular(2)*Modular(n-1)*fac[2*n-2]/mexp(Modular(2), n) << endl;
		return;
	}


	bool winner = (two_cnt != 0);
	foru(i, n) v[i] = (v[i] != 1);

	if(!winner) foru(i, n-1) swap(v[i], v[i+1]);

	Modular ans = 0;

	bool fst = v[0];
	vec<int> segs;
	int st_idx = 0;
	int even_cnt = 0;

	foru(i, n){
		if(i == 0 || v[i-1] != v[i]) segs.pb(1);
		else segs.back()++;
	}

	for(auto i : segs) even_cnt += ((i&1) == 0);

	foru(_i, n/2){
		debug(st_idx);
	
		int len = sz(segs)-st_idx;

		if(!(fst^(len&1))) goto skip;
		if(even_cnt >= 2) goto skip;
		if(even_cnt == 1 && segs[st_idx]&1) goto skip;

		ans += anachronic_help(n, len, segs[st_idx]-1);
		ans += duble_help(n, len, segs[st_idx]-1);

		skip:;

		int todo = 2;

		while(todo != 0){
			int op = min(todo, segs[st_idx]);
			todo -= op;
			
			len = sz(segs)-st_idx;

			if((len&1) == 0) segs.pb(0), even_cnt++;

			even_cnt -= ((segs[st_idx]&1) == 0);
			even_cnt -= ((segs.back()&1) == 0);

			segs[st_idx] -= op;
			segs.back() += op;

			even_cnt += ((segs[st_idx]&1) == 0);
			even_cnt += ((segs.back()&1) == 0);

			if(segs[st_idx] == 0){
				st_idx ++;
				fst = !fst;
				even_cnt--;
			}
		}
	}

	cout << ans/mexp(Modular(2), n) << endl;
}

int main()
{
	cin.tie(0); cout.tie(0);
	ios_base::sync_with_stdio(0);

	srand(time(NULL));

	fac[0] = 1;
	fors(i, N, 1) fac[i] = fac[i-1]*Modular(i);

	twoexp[0] = 1;
	fors(i, N, 1) twoexp[i] = twoexp[i-1]*Modular(2);

	int t; cin >> t;
	foru(_i, t)
		solve();

	return 0;
}