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#include <bits/stdc++.h>
using namespace std;
using ind = long long;
using cind = const ind;
#define FOR(i,l,r) for(ind i = (l); i <= (r); i++)
#define FORD(i,l,r) for(ind i = (l); i >= (r); i--)
#define DEBUG_ON false
#define debug if constexpr(DEBUG_ON)
#define err debug cerr

ind MOD=1'000'000'007;

ind pow2(ind a, ind p){
    ind w=1;
    while(p > 0){
        if(p%2==1) w = (w * a) % MOD;
        a = (a*a)%MOD;
        p/=2;
    }
    return w;
}
ind inversed(ind a){
    return pow2(a,MOD-2);
}

ind v[2'000'001];
ind factorial[4'000'001];
ind inverse_factorial[4'000'001];
ind filling[2'000'001];

struct mod_ind{
    ind v;
    void operator=(ind a){v=a%MOD;}
    mod_ind operator*(ind a){return mod_ind({(v*a)%MOD});}
};
void solve(){
    ind N;
    cin >> N;
    FOR(i,1,2*N) cin >> v[i];
    bool a=true;
    FOR(i,1,2*N) if(v[i] != 1) a=false;
    if(a){
        ind wyn = 0;
        if(N>=2) wyn += (mod_ind({2*N})*(N)*(N-1)*(4*N-3)*(4*N-4)*(4*N-5)*filling[2*N-3]).v;
        wyn += (mod_ind({2*N})*(N)*(4*N-3)*filling[2*N-2]).v;
        cout << wyn%MOD << endl;
        return;
    }
    bool a0=false;
    bool a2=false;
    FOR(i,1,2*N) if(v[i]==0) a0=true;
    FOR(i,1,2*N) if(v[i]==2) a2=true;
    if(a0 and a2){
        cout << "0\n";
        return;
    }
    if(a2){
        FOR(i,1,2*N) if(v[i]==2) v[i]=0;
        FOR(i,2,2*N) swap(v[i-1],v[i]);
        a2=false;
        a0=true;
    }
    a=true;
    FOR(i,1,2*N) if(v[i] != 0) a=false;
    if(a){
        ind wyn = 0;
        if(N >= 2) wyn += (mod_ind({2*N})*(N-1)*(4*N-2)*(4*N-3)*filling[2*N-2]).v;
        wyn += (mod_ind({2*N})*filling[2*N-1]).v;
        cout << wyn%MOD << endl;
        return;
    }
    FOR(i,2,2*N){
        if(v[i]==1 and v[i-1]==0) if(i%2 == 0){cout << "0\n"; return;}
        if(v[i]==0 and v[i-1]==1) if(i%2 == 1){cout << "0\n"; return;}
    }
    if(v[1]==0 and v[2*N]==1) {cout << "0\n"; return;}
    ind e = 2*N;
    ind add = 0;
    vector<pair<ind,ind>> groups;
    while(v[1] == v[e]){
        e--;
        add++;
    }
    ind len = 1;
    FOR(i,2,e){
        if(v[i] == v[i-1]){
            len++;
            continue;
        }
        groups.push_back({v[i-1],len+add});
        len=1;
        add=0;
    }
    groups.push_back({v[e], len+add});
    len=1;
    add=0;

    ind w1=0;
    // w1 += (mod_ind({ind(groups.size())/2}) 
    // * factorial[4*N-(groups.size()/2)] 
    // * inverse_factorial[4*N-groups.size()] 
    // * filling[2*N-groups.size()]).v;

    ind w2=0;
    // FOR(j,0,ind(groups.size())-1){
    //     if(groups[j].first==0) continue;
    //     len = groups[j].second;
    //     w1 += (mod_ind({factorial[4*N-(groups.size()/2)]})
    //     * inverse_factorial[4*N-groups.size()] 
    //     * filling[2*N-groups.size()]).v;
    //     if(len > 1)
    //     w1 -= (mod_ind({factorial[4*N-(groups.size()/2)-1]})
    //     * (len-1)
    //     * inverse_factorial[4*N-groups.size()-2] 
    //     * filling[2*N-groups.size()-1]).v;


    // }

    // cerr << "groups " << groups.size() << endl;
    FOR(j,0,ind(groups.size())-1){
        if(groups[j].first==0) continue;
        len = groups[j].second;
        w1 += (mod_ind({factorial[4*N-groups.size()]})
        * inverse_factorial[4*N-2*groups.size()] 
        * filling[2*N-groups.size()]).v;
        if(len > 1)
        w1 -= (mod_ind({factorial[4*N-groups.size()-1]})
        * (len-1)
        * inverse_factorial[4*N-2*groups.size()-2] 
        * filling[2*N-groups.size()-1]).v;
        // cerr << w1 << endl;
    }

    cout << (w1 + w2)%MOD << endl;
}
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cerr << "hm" << endl;
    factorial[0]=1;
    FOR(i,1,4'000'00) factorial[i] = (factorial[i-1]*i)%MOD;
    filling[0]=1;
    FOR(i,1,2'000'00) filling[i] = (((filling[i-1] * (i))%MOD) * (2*i-1)) % MOD;//filling[i] = (filling[i-1] * (2*i) * (2*i-1) / 2) % MOD;
    inverse_factorial[0]=1;
    FOR(i,1,4'000'00) inverse_factorial[i] = inversed(factorial[i]);
    cerr << "nah" << endl;
    ind T;
    cin >> T;
    FOR(ti,1,T) solve();
}