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#ifdef LOC
#include "debuglib.hpp"
#else
#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
#define deb(...)
#define DBP(...)
#endif
using namespace std;
using   ll         = long long;
using   vi         = vector<int>;
using   pii        = pair<int, int>;
#define pb           push_back
#define mp           make_pair
#define x            first
#define y            second
#define rep(i, b, e) for (int i = (b); i < (e); i++)
#define each(a, x)   for (auto& a : (x))
#define all(x)       (x).begin(), (x).end()
#define sz(x)        int((x).size())

constexpr int MAX_N = int(1e6);
constexpr int MOD = int(1e9) + 7;

ll modPow(ll a, ll e, ll m) {
	ll t = 1 % m;
	while (e) {
		if (e % 2) t = t*a % m;
		e /= 2; a = a*a % m;
	}
	return t;
}

struct Zp {
	ll x;
	Zp() : x(0) {}
	Zp(ll a) : x(a%MOD) { if (x < 0) x += MOD; }
	#define OP(c,d) Zp& operator c##=(Zp r) { x = x d; return *this; } Zp operator c(Zp r) const { Zp t = *this; return t c##= r; }
	OP(+, +r.x - MOD*(x+r.x >= MOD));
	OP(-, -r.x + MOD*(x-r.x < 0));
	OP(*, *r.x % MOD);
	OP(/, *r.inv().x % MOD);
	Zp operator-() const { return Zp()-*this; }
	Zp inv() const { return pow(MOD-2); }
	Zp pow(ll e) const{ return modPow(x,e,MOD); }
	void print() { cerr << x; }
};

vector<Zp> fac, two, twoInv;

Zp solveOrdered(int n, vi target) {
	int mn = *min_element(all(target));
	int mx = *max_element(all(target));
	if (mn == 0 && mx == 2) return 0;
	if (mn == mx) {
		if (mn == 1) return fac[n*4-3] * (n*2) * (n*2) * (n*2-1) * 2;
		return fac[n*4-2] * (n*2) * (n*2-1);
	}
	if (mn == 0) {
		each(e, target) e = 2-e;
		rotate(target.begin(), target.begin()+1, target.end());
	}

	Zp ans = 0;
	deque<pii> segs; // (value, count)
	int numEven = 0;

	auto push = [&](int e) {
		if (segs.empty() || segs.back().x != e) {
			segs.pb({e, 1});
		} else {
			numEven += (++segs.back().y % 2 == 0 ? 1 : -1);
		}
	};

	auto pop = [&]() {
		assert(!segs.empty());
		int e = segs.front().x;
		if (--segs.front().y == 0) {
			segs.pop_front();
		} else {
			numEven += (segs.front().y % 2 == 0 ? 1 : -1);
		}
		return e;
	};

	each(e, target) {
		push(e);
	}

	rep(offset, 0, n) {
		int t = segs.front().y;
		if (segs.back().x == 1 && numEven == (t%2 == 0)) {
			int k = sz(segs);
			int takenRight = k / 2;
			int availRight = max((n*2-t+1)/2*2 - takenRight, 0);
			int availLeft = t/2*2;
			if (n*4-k-1 >= 0) ans += two[k] * availRight * fac[n*4-k-1];
			if (n*4-k-2 >= 0) ans += two[k] * availLeft * (availLeft+availRight-1) * fac[n*4-k-2];
		}
		rep(i, 0, 2) push(pop());
	}

	return ans;
}

Zp solve(int n, vi target) {
	return solveOrdered(n, move(target)) * twoInv[n*2];
}

void precomp() {
	fac.resize(MAX_N*4+5);
	two.resize(MAX_N*4+5);
	twoInv.resize(MAX_N*4+5);

	fac[0] = 1;
	two[0] = 1;
	twoInv[0] = 1;

	fac[1] = 1;
	two[1] = 2;
	twoInv[1] = two[1].inv();

	rep(i, 2, sz(fac)) {
		fac[i] = fac[i-1] * i;
		two[i] = two[i-1] * 2;
		twoInv[i] = twoInv[i-1] * twoInv[1];
	}
}

int main() {
	cin.sync_with_stdio(0); cin.tie(0);
	precomp();
	int t; cin >> t;
	while (t--) {
		int n; cin >> n;
		vi target(n*2);
		each(e, target) cin >> e;
		cout << solve(n, move(target)).x << '\n';
	}
}