#include <cstdio>
#include <cstring>
#include <algorithm>
#define F first
#define S second
using namespace std;
typedef long long LL;
typedef pair<LL, LL> PLL;
const LL MOD = 1e9 + 7;
const int N = 2e5 + 10;
int n;
PLL a[N];
int ap;
LL F[N], Finv[N], inv[N];//F是阶乘，Finv是逆元的阶乘 
void init(){
    inv[1] = 1;
    for(int i = 2; i < N; i ++){
        inv[i] = (MOD - MOD / i) * 1ll * inv[MOD % i] % MOD;
    }
    F[0] = Finv[0] = 1;
    for(int i = 1; i < N; i ++){
        F[i] = F[i-1] * 1ll * i % MOD;
        Finv[i] = Finv[i-1] * 1ll * inv[i] % MOD;
    }
}
LL comb(int n, int m){//comb(n, m)就是C(n, m) 
    if(m < 0 || m > n) return 0;
    return F[n] * 1ll * Finv[n - m] % MOD * Finv[m] % MOD;
}
int main(){
    init();
    int T;
    scanf("%d", &T);
    while(T --){
        scanf("%d", &n);
        int lst = -1, tmp;
        ap = 0;
        for(int i = 0; i < 2*n; ++ i){
            scanf("%d", &tmp);
            if(tmp != lst){
                a[ap ++] = PLL(tmp, 1);
                lst = tmp;
            }
            else{
                ++ a[ap-1].S;
            }
        }
        int ls = 0;
        LL ans = 1;
        for(int i = 0; i < ap; ++ i){
            if(ls == 0){
                if(a[i].S & 1){
                    ans = ans * comb(a[i].S, a[i].S/2) * 2 % MOD;
                    ls = 1;
                }
                else{
                    ans = ans * comb(a[i].S, a[i].S/2) % MOD;
                    ls = 0;
                }
            }
            else{
                if(a[i].S & 1){
                    ans = ans * comb(a[i].S, a[i].S/2) % MOD;
                    ls = 0;
                }
                else{
                    ans = ans * (comb(a[i].S, a[i].S/2) + comb(a[i].S, a[i].S/2-1)) % MOD;
                    ls = 1;
                }
            }
        }
        printf("%I64d\n", ans);
    }
}