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#include <iostream>
#include <vector>
#include <unordered_map>

using namespace std;

const int MOD = 1e9 + 7;
const int N = 1e6;
const long long HALF = 500000004;
vector<long long> factorials(4 * N + 1);
vector<long long> powers(2 * N + 2);

void computeFactorials() {
    factorials[0] = 1;
    for (int i = 1; i <= 4 * N; ++i) {
        factorials[i] = (factorials[i - 1] * i) % MOD;
    }
}

void computePowersOfHalf() {
    powers[0] = 2;
    powers[1] = 1;
    for (int i = 1; i <= 2 * N; ++i) {
        powers[i + 1] = (powers[i] * HALF) % MOD;
    }
}

long long mul(long long a, long long b) {
    return (a * b) % MOD;
}

void test() {
    int n;
    cin >> n;
    vector<int> a(2 * n);
    bool zero = false, one = false, two = false;
    for (int i = 0; i < 2 * n; ++i) {
        cin >> a[i];
        if (a[i] == 0) zero = true;
        else if (a[i] == 1) one = true;
        else two = true;
        if (a[i] > 1) {
            a[i] = 0;
        }
    }
    if (zero && two) {
        cout << 0 << endl;
        return;
    }
    if (!one) {
        cout << mul(mul(mul(n, 2 * n - 1), factorials[4 * n - 2]), powers[2 * n]) << endl;
        return;
    }
    if (!zero && !two) {
        cout << mul(mul(mul(mul(n, n), 2 * n - 1), factorials[4 * n - 3]), powers[2 * n - 2]) << endl;
        return;
    }
    int parity = two ? 1 : 0;

    int changes = 0;
    int blockSize = 1;
    int firstBlockSize = 1;
    for (int i = 1; i < 2 * n; ++i) {
        if (a[i] != a[i - 1]) {
            if (changes > 0 && blockSize % 2 == 0) {
                cout << 0 << endl;
                return;
            }
            changes++;
            blockSize = 1;
        } else {
            blockSize++;
        }
        if (changes == 0) {
            firstBlockSize++;
        }
    }
    if (a[2 * n - 1] == a[0]) {
        if ((firstBlockSize + blockSize) % 2 == 0) {
            cout << 0 << endl;
            return;
        }
    } else {
        if (blockSize % 2 == 0) {
            cout << 0 << endl;
            return;
        }
        changes++;
    }

    long long result = 0;
    int greatestPointer = 0;
    int lowestPointer = 0;
    bool overflow = false;
    while (greatestPointer < 2 * n) {
        // cout << "greatestPointer: " << greatestPointer << ", a: " << a[greatestPointer] << endl;
        if (a[greatestPointer] == 1 && greatestPointer % 2 == parity) {
            if (a[greatestPointer] == a[(greatestPointer - 1 + 2 * n) % (2 * n)] && a[greatestPointer] != a[(greatestPointer - 2 + 2 * n) % (2 * n)]) {
                cout << 0 << endl;
                return;
            }
            int cards = a[greatestPointer] != a[(greatestPointer + 1) % (2 * n)] ? changes : changes + 1;
            if (!overflow && lowestPointer <= greatestPointer) {
                lowestPointer = (greatestPointer + 1) % (2 * n);
            }
            while (a[lowestPointer] == a[(lowestPointer + 1) % (2 * n)]) {
                lowestPointer = (lowestPointer + 1) % (2 * n);
            }
            int fromLowestToGreatest = (greatestPointer - lowestPointer + 2 * n) % (2 * n);
            int fromGreatestToLowest = (lowestPointer - greatestPointer + 2 * n) % (2 * n) - 1;
            long long positionsFromLowestToGreatest = (fromLowestToGreatest + 1) / 2; // TODO check if this is correct
            long long positionsFromGreatestToLowest = (fromGreatestToLowest + 1) / 2; // TODO check if this is correct
            long long ourPositionsFromLowestToGreatest = cards / 2; // TODO check if this is correct
            // cout << "changes: " << changes << " cards: " << cards << " parity: " << parity << " greatest: " << greatestPointer << ", lowest: " << lowestPointer << ", a: " << a[greatestPointer] << ", fromLowestToGreatest: " << fromLowestToGreatest << ", fromGreatestToLowest: " << fromGreatestToLowest << " positionsFromLowestToGreatest: " << positionsFromLowestToGreatest << ", positionsFromGreatestToLowest: " << positionsFromGreatestToLowest << " ourPositionsFromLowestToGreatest: " << ourPositionsFromLowestToGreatest << endl;

            // cout << "factorial: " << factorials[4 * n - 2 - cards] << " power: " << powers[2 * n - cards + 1] << endl;
            // cout << "component1: " << (2 * positionsFromLowestToGreatest - ourPositionsFromLowestToGreatest) * (4 * n - cards - 1) % MOD << endl;
            // cout << "component2: " << 4 * positionsFromGreatestToLowest * (n - 1 - ourPositionsFromLowestToGreatest) % MOD << endl;
            // cout << "component3: " << 2 * positionsFromGreatestToLowest * (1 + ourPositionsFromLowestToGreatest) % MOD << endl;

            result = (result + mul(mul(factorials[4 * n - 2 - cards], powers[2 * n - cards + 1]), ((2 * positionsFromLowestToGreatest - ourPositionsFromLowestToGreatest) * (4 * n - cards - 1) + 4 * positionsFromGreatestToLowest * (n - 1 - ourPositionsFromLowestToGreatest) + 2 * positionsFromGreatestToLowest * (1 + ourPositionsFromLowestToGreatest)) % MOD)) % MOD;
        }
        greatestPointer++;
    }
    cout << result << endl;
}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    computeFactorials();
    computePowersOfHalf();

    int t;
    cin >> t;
    for (int i = 0; i < t; ++i) {
        test();
    }
}