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#include <bits/stdc++.h>


using namespace std;


const int MOD = 1'000'000'007;
const int INV2 = (MOD + 1) / 2;

const int N = 1'000'000;

vector <int> powInv2(2 * N + 1), fact(4 * N + 1);


void prepare() {
    powInv2[0] = 1;
    for (int i = 1; i <= 2 * N; i++) {
        powInv2[i] = ((long long) INV2 * powInv2[i - 1]) % MOD;
    }

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

int solveLast(int n, deque <int> &blocks) {
    int nBlocks = blocks.size();
    int nBlocksHalf = nBlocks / 2;
    int ways = 2 * (n - nBlocksHalf);

    int cnt1 = blocks.back() / 2;
    ways = ((long long) cnt1 * (4 * n - 4 - 2 * nBlocksHalf) + ways) % MOD;

    int prevStart = blocks.back() - 1;
    if (prevStart % 2 != (nBlocks + 1) % 2) {
        prevStart++;
    }

    int cnt2 = (2 * n - prevStart + 1) / 2 - nBlocksHalf;
    ways = ((long long) cnt2 * (8 * n - 4 - 2 * nBlocks) + ways) % MOD;
    ways = ((long long) (nBlocks / 2) * (4 * n - 1 - nBlocks) + ways) % MOD;

    ways = ((long long) ways * powInv2[2 * n - nBlocks]) % MOD;
    ways = ((long long) ways * fact[4 * n - 2 - nBlocks]) % MOD;

    return ways;
}

int solveAllZero(int n) {
    int ways = ((long long) (2 * n - 1) * powInv2[2 * n - 1]) % MOD;

    ways = ((long long) ways * fact[4 * n - 2]) % MOD;
    ways = ((long long) ways * n) % MOD;

    return ways;
}

void rotateBlocks(int &numEvenBlocks, deque <int> &blocks) {
    if (blocks.size() == 1) {
        return ;
    }

    if (blocks.size() % 2) {
        if (blocks.back() % 2) {
            numEvenBlocks++;
        } else {
            numEvenBlocks--;
        }

        blocks.back()++;
    } else {
        blocks.push_back(1);
    }

    if (blocks.front() % 2) {
        numEvenBlocks++;
    } else {
        numEvenBlocks--;
    }

    blocks.front()--;

    if (!blocks.front()) {
        blocks.pop_front();
        numEvenBlocks--;
    }
}

int solveOdd(int n, vector <int> &a) {
    int aMax = *max_element(a.begin(), a.end());
    if (aMax == 0) {
        return solveAllZero(n);
    } else if (aMax == 2) {
        return 0;
    }

    int currBlock = 1;
    deque <int> blocks;

    for (int i = 2 * n - 2; i >= 0; i--) {
        if (a[i] != a[i + 1]) {
            blocks.push_back(currBlock);
            currBlock = 0;
        }

        currBlock++;
    }

    blocks.push_back(currBlock);

    int numEvenBlocks = 0;
    for (int block : blocks) if (block % 2 == 0) {
        numEvenBlocks++;
    }

    int ans = 0;
    for (int p = 2 * n - 1; p >= 0; p -= 2) {
        if (a[p] == 1 && numEvenBlocks == (blocks.back() % 2 == 0)) {
            ans += solveLast(n, blocks);
            if (ans >= MOD) {
                ans -= MOD;
            }
        }

        rotateBlocks(numEvenBlocks, blocks);
        rotateBlocks(numEvenBlocks, blocks);
    }

    return ans;
}

int solve(int n, vector <int> &a) {
    int ans = 0;
    for (int r = 0; r <= 1; r++) {
        for (int &ai : a) {
            ai = 2 - ai;
        }

        ans += solveOdd(n, a);
        if (ans >= MOD) {
            ans -= MOD;
        }

        a.push_back(a[0]);
        a.erase(a.begin());
    }

    return ans;
}

int main() {
    ios_base::sync_with_stdio(false);
    prepare();

    int t;
    cin >> t;

    while (t--) {
        int n;
        cin >> n;

        vector <int> a(2 * n);
        for (int &ai : a) {
            cin >> ai;
        }

        cout << solve(n, a) << '\n';
    }

    return 0;
}