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

#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define all(x) begin(x), end(x)
#define sz(x) int((x).size())
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

#ifdef LOCAL
auto operator<<(auto& o, auto x) -> decltype(x.first, o);
auto operator<<(auto& o, auto x) -> decltype(x.end(), o) {
  o << "{";
  for (int i = 0; auto y : x) o << ", " + !i++ * 2 << y;
  return o << "}"; }
auto operator<<(auto& o, auto x) -> decltype(x.first, o) {
  return o << "(" << x.first << ", " << x.second << ")"; }
void __print(auto... x) { ((cerr << x << " "), ...) << endl; }
#define debug(x...) __print("[" #x "]:", x)
#else
#define debug(...) 2137
#endif

template<int M, int R>
struct Mod {
  static const int mod = M, rt = R;
  int x;
  Mod(ll y = 0) : x(y % M) { x += (x < 0) * M; }
  Mod& operator+=(Mod o) {
    if ((x += o.x) >= M) x -= M;
    return *this; }
  Mod& operator-=(Mod o) {
    if ((x -= o.x) < 0) x += M;
    return *this; }
  Mod& operator*=(Mod o) {
    x = 1ll * x * o.x % M;
    return *this; }
  Mod& operator/=(Mod o) { return *this *= o.inv(); }
  friend Mod operator+(Mod a, Mod b) { return a += b; }
  friend Mod operator-(Mod a, Mod b) { return a -= b; }
  friend Mod operator*(Mod a, Mod b) { return a *= b; }
  friend Mod operator/(Mod a, Mod b) { return a /= b; }
  auto operator<=>(const Mod&) const = default;
  Mod pow(ll n) const {
    Mod a = x, b = 1;
    for (; n; n /= 2, a *= a) if (n % 2) b *= a;
    return b; }
  Mod inv() const { assert(x); return pow(M - 2); }
  friend ostream& operator<<(ostream& os, Mod x) {
    return os << x.x; }
};
using mint = Mod<1000000007, -1>;

const int nax = 4 * 1e6 + 10;
mint f[nax], invf[nax], invpw[nax];

mint count(int n, int singles, int pairs) {
  n *= 4;
  n -= singles + 2 * pairs;
  return f[n] * invpw[(n - singles) / 2];
}

void solve() {
  int n;
  cin >> n;
  vector<int> v(2 * n);
  for(int& i : v) cin >> i;
  int mx = *max_element(all(v));
  if(mx == 2) {
    for(int i = 0; i < 2 * n; i++) {
      v[i] = 2 - v[i];
    }
    rotate(v.begin(), v.end() - 1, v.end());
    mx = *max_element(all(v));
    if(mx == 2) {
      cout << 0 << '\n';
      return;
    }
  }
  
  vector<int> pos(2 * n);
  int start = 0;
  for(int i = 1; i < 2 * n; i++) {
    if(v[i] != v[i - 1]) {
      start = i - 1;
      break;
    }
  }
  int num_bl = 0, prv = -1, lst;
  bool ok = 1;
  for(int i = start + 2 * n; i > start; i--) {
    int id = i % (2 * n);
    if(prv != v[id]) {
      num_bl++;
      lst = id;
      if(v[id] == id % 2) ok = 0;
    }
    prv = v[id];
    pos[id] = lst;
  }
  
  mint ans = 0;
  if(num_bl == 1) {
    if(v[0] == 0) {
      ans = count(n, 0, 1) + (n - 1) * count(n, 2, 0);
      ans *= n;
    } else {
      ans = n * (count(n, 1, 1) + (n - 1) * count(n, 3, 0));
      ans *= 2 * n;
    }
  } else if(ok) {
    for(int i = 0; i < 2 * n; i++) {
      if(i % 2 == 0 && v[i] == 1) {
        int use = num_bl + 1;
        int len = (pos[i] + 2 * n - i) % (2 * n);
        if(pos[i] == i) {
          use = num_bl;
          int nxt = (i + 1) % (2 * n);
          len = (pos[nxt] + 2 * n - i) % (2 * n);
        }
        
        ans += use / 2 * count(n, use - 1, 1);
        ans += (n - use / 2 - len / 2) * count(n, use + 1, 0);
        mint x = (1 + use / 2) * count(n, use, 1);
        x += (n - 1 - use / 2) * count(n, use + 2, 0);
        ans += len / 2 * x;
      }
    }
  }
  
  cout << ans << '\n';
}

int main() {
  cin.tie(0)->sync_with_stdio(0);
  
  f[0] = invpw[0] = 1;
  mint inv = mint(2).inv();
  for(int i = 1; i < nax; i++) {
    f[i] = f[i - 1] * i;
    invpw[i] = invpw[i - 1] * inv;
  }
  invf[nax - 1] = f[nax - 1].inv();
  for(int i = nax - 2; i >= 0; i--) {
    invf[i] = invf[i + 1] * (i + 1);
  }

  int t;
  cin >> t;
  while(t--) solve();
}