#include <bits/stdc++.h>
#define MOD 1000000007
using namespace std;
int T, n, a[200005], tot, mid, fac[200005], nev[200005], ans;
int C(int x, int y) {return (int)(1LL * fac[x] * nev[y] % MOD * nev[x - y] % MOD);}
int fpm(int x, int y)
{
  int ret = 1;
  while (y)
  {
    if (y & 1) ret = 1LL * ret * x % MOD;
    x = 1LL * x * x % MOD;
    y >>= 1;
  }
  return ret;
}
int main()
{
  fac[0] = nev[0] = 1;
  for (int i = 1; i <= 200000; i++)
  {
    fac[i] = 1LL * fac[i - 1] * i % MOD;
    nev[i] = fpm(fac[i], MOD - 2);
  }
  scanf("%d", &T);
  while (T--)
  {
    scanf("%d", &n);
    n *= 2;
    for (int i = 1; i <= n; i++) scanf("%d", a + i);
    ans = 1;
    for (int i = 1; i <= n; i++)
    {
      int j = i;
      while (j < n && a[j + 1] == a[i]) j++;
      tot = j - i + 1;
      mid = tot / 2;
      if (i % 2 == 0 && j % 2 == 1) ans = 1LL * ans * (C(tot, mid) + C(tot, mid + 1)) % MOD;
      else if (i % 2 == 1 && j % 2 == 1) ans = ans * 1LL * C(tot, mid) * 2 % MOD;
      else ans = 1LL * ans * C(tot, mid) % MOD;
      i = j;
    }
    printf("%d\n", ans);
  }
}