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#include <bits/stdc++.h>

using namespace std;
#define pb push_back
#define st first
#define nd second
typedef long long ll;
typedef long double ld;
const ll I = 1'000'000'000'000'000'000LL;
const int II = 2'000'000'000;
const ll M = 1'000'000'007LL;
const int N = 1'000'007;
int tab[4 * N];
int nxt[4 * N], il[4 * N][2];

ll sil[4 * N];

void Pre(int n)
{
    sil[0] = 1LL;
    for(int i = 1; i <= n; ++i)
        sil[i] = (sil[i - 1] * (ll)i) % M;
}

ll QP(ll a, ll n)
{
    ll ans = 1LL;
    while(n > 0LL)
    {
        if(n % 2LL == 1LL)
            ans = (ans * a) % M;
        a = (a * a) % M;
        n /= 2LL;
    }
    return ans;
}

ll C(ll il, ll il2)
{
    return (sil[il] * QP(QP(2, il2), M - 2LL)) % M;
}

void Solve()
{
    int n;
    int cz0 = 0, cz1 = 0, cz2 = 0;
    cin >> n;
    for(int i = 1; i <= 2 * n; ++i)
    {
        cin >> tab[i];
        if(tab[i] == 0) cz0 = 1;
        if(tab[i] == 1) cz1 = 1;
        if(tab[i] == 2) cz2 = 1;
    }
    if(cz0 && cz2)
    {
        cout << 0 << "\n";
        return;
    }
    if(cz1 == 0)
    {
        ll ans = (ll)n * C(n * 4 - 2, 2 * n - 1);
        ans += (((ll)n * (ll)(n - 1)) % M) * C(n * 4 - 2, 2 * n - 2);
        ans %= M;
        cout << ans << "\n";
        return;
    }
    if(cz0)
        for(int i = 1; i <= 2 * n; ++i)
            tab[i] = 2 - tab[i];
    else
        for(int i = 2; i <= 2 * n; ++i)
            swap(tab[1], tab[i]);
    for(int i = 1; i <= 2 * n; ++i)
        tab[i + 2 * n] = tab[i];

    for(int i = 4 * n; i >= 1; --i)
    {
        nxt[i] = i + 1;
        if(tab[i] == tab[i + 1])
            nxt[i] = nxt[i + 1];
        else
            ++il[i][(i + tab[i]) % 2];
        nxt[i] = min(nxt[i], i + 2 * n - 1);
    }
    for(int i = 1; i <= 4 * n; ++i)
        for(int r = 0; r < 2; ++r)
            il[i][r] += il[i - 1][r];
    ll ans = 0LL;
    for(int i = 1; i <= 2 * n; i += 2)
    {
        if(tab[i] != 1) continue;
        int ar = (tab[i] + i) % 2;
        int ils = il[i + 2 * n - 1][ar] - il[i][ar] + 1;
        if((il[i + 2 * n - 1][ar ^ 1] - il[i - 1][ar ^ 1]) > 0) continue;

        // cout << "\nC: " << i << " " << ils << "\n";

        int d = nxt[i + 1] - i - 1;
        ll ilp = ((d + (tab[i + 1] % 2)) / 2LL);
        ll p1 = (ils) / 2LL;
        ll p2 = (n - ilp) - p1;

        // cout << d << " " << ilp << " " << p1 << " " << p2 << "\n";

        ans += ilp * C(4 * n - ils - 2, 2 * n - ils - 1);
        ans += ((ilp * (ll)(n - p1 - 1)) % M) * C(4 * n - ils - 2, 2 * n - ils - 2);
        ans += ((ilp * (ll)(p1)) % M) * C(4 * n - ils - 2, 2 * n - ils - 1);
        ans %= M;
        ans += p1 * C(4 * n - ils - 1, 2 * n - ils);
        ans += p2 * C(4 * n - ils - 1, 2 * n - ils - 1);
        ans %= M;
    }
    if(cz0 == 0 && cz2 == 0)
        ans = (ans * 2LL) % M;
    cout << ans << "\n";
    for(int i = 1; i <= 4 * n; ++i)
        for(int r = 0; r < 2; ++r)
            il[i][r] = 0;
}

int main()
{
    Pre(4*1000*1000+4);
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int t; cin >> t;
    while(t--)
        Solve();

    return 0;
}