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#include <bits/stdc++.h>
using namespace std;

const int MOD = 1'000'000'007;
int mul(int a, int b) {
	return (long long) a * b % MOD;
}
int my_pow(int a, int b) {
	int r = 1;
	while (b) {
		if (b % 2) {
			r = mul(r, a);
		}
		a = mul(a, a);
		b /= 2;
	}
	return r;
}
int my_inv(int a) {
	return my_pow(a, MOD - 2);
}
int my_div(int a, int b) {
	return mul(a, my_inv(b));
}

void test_case() {
	int n;
	cin >> n;
	
	vector<int> fac(4 * n + 1);
	fac[0] = 1;
	for (int i = 1; i < (int) fac.size(); i++) {
		fac[i] = mul(i, fac[i-1]);
	}
	
	vector<int> a(2 * n);
	for (int& x : a) {
		cin >> x;
	}
	int MIN = *min_element(a.begin(), a.end());
	int MAX = *max_element(a.begin(), a.end());
	const int DIVIDE = my_inv(my_pow(2, 2 * n));
	if (MIN == 2 || MAX == 0) {
		// This group gets MAX and MAX-1.
		int ans = (long long) 2 * n % MOD * (2 * n - 1) % MOD * fac[4*n-2] % MOD * DIVIDE % MOD;
		cout << ans << "\n";
		return;
	}
	if (MIN == 1 && MAX == 1) {
		// Choose one group. This group takes MAX, the other group takes MAX-1 and MAX-2.
		int ans = (long long) 2 * 2 * n * 2 * n % MOD * (2 * n - 1) % MOD * fac[4*n-3] % MOD * DIVIDE % MOD;
		cout << ans << "\n";
		return;
	}
	if (MIN == 0 && MAX == 2) {
		cout << "0\n";
		return;
	}
	int diffs = 0;
	for (int i = 0; i < (int) a.size(); i++) {
		if (a[i] != a[(i+1)%(int)a.size()]) {
			diffs++;
			if ((i % 2 == 0) != (a[i] == MAX)) {
				cout << "0\n";
				return;
			}
		}
	}
	int ans = 0;
	int ones = 0;
	for (int i = 0; i < (int) a.size() && a[i] == 1; i++) {
		ones++;
	}
	for (int i = (int) a.size() - 1; i >= 0; --i) {
		if (a[i] != 1) {
			ones = 0;
			continue;
		}
		ones++;
		if (ones % 2 == 1) {
			// put MAX here
			if (ones == 1) {
				// standard
				int nxt_range = 0;
				for (int j = (i + 1) % (int) a.size(); a[j] != 1; j = (j + 1) % (int) a.size()) {
					nxt_range++;
				}
				assert(nxt_range % 2 == 1);
				const int TMP = my_pow(2, diffs);
				int x = (long long) TMP * (2 * n - diffs / 2 - nxt_range / 2 * 2) % MOD * fac[4*n-diffs-1] % MOD * DIVIDE % MOD;
				int y = (long long) TMP * (nxt_range / 2 * 2) % MOD * (2 * n - diffs / 2 - 1) % MOD * fac[4*n-diffs-2] % MOD * DIVIDE % MOD;
				ans = (ans + x + 0LL + y) % MOD;
			}
			else {
				// special
				const int TMP = my_pow(2, diffs + 1);
				int x = (long long) TMP * (2 * n - diffs / 2 - ones / 2 * 2) % MOD * fac[4*n-diffs-2] % MOD * DIVIDE % MOD;
				int y = (long long) TMP * (ones / 2 * 2) % MOD * (2 * n - diffs / 2 - 1) % MOD * fac[4*n-diffs-3] % MOD * DIVIDE % MOD;
				ans = (ans + x + 0LL + y) % MOD;
			}
		}
	}
	cout << ans << "\n";
	
	// int ans = 0;
	// int ones = 0;
	// for (int i = (int) a.size() - 1; i >= 0 && a[i] == 1; --i) {
		// ones++;
	// }
	// for (int i = 0; i < (int) a.size(); i++) {
		// if (a[i] != 1) {
			// ones = 0;
			// continue;
		// }
		// ones++;
		
	// }
	// int ans = (long long) diffs / 2 * my_pow(2, diffs - 1) % MOD * fac[4*n-diffs] % MOD * DIVIDE % MOD;
	// int spec = 0;
	// for (int i = 0; i < (int) a.size(); i++) {
		// if (a[i] == 1) {
			// spec++;
		// }
	// }
	// spec -= diffs / 2;
	// assert(spec % 2 == 0);
	// spec /= 2;
	// int ans2 = (long long) spec * my_pow(2, diffs + 1) % MOD * fac[4*n-(diffs+1)] % MOD * DIVIDE % MOD;
	// ans2 = 0;
	// cout << (ans+ans2) % MOD << "\n";
}

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int T;
	cin >> T;
	while (T--) {
		test_case();
	}
}