#include<bits/stdc++.h> 
#define For(i,j,k) for (int i=(int)(j);i<=(int)(k);i++)
#define Rep(i,j,k) for (int i=(int)(j);i>=(int)(k);i--)
#define pii pair<int,int>
#define pll pair<ll,ll>
#define ll long long
#define fi first
#define se second
#define PB push_back
#define uint unsigned
#define ull unsigned ll 
using namespace std;
const int mo=1000000007;
const int N=1000005;
int fac[N],inv[N];
void init(){
    fac[0]=inv[0]=inv[1]=1;
    For(i,2,N-1) inv[i]=1ll*inv[mo%i]*(mo-mo/i)%mo;
    For(i,1,N-1) fac[i]=1ll*fac[i-1]*i%mo;
    For(i,1,N-1) inv[i]=1ll*inv[i-1]*inv[i]%mo;
}
int C(int x,int y){
    return 1ll*fac[x]*inv[y]%mo*inv[x-y]%mo;
}
int n,a[N],q[N];
int f[N][2];
void solve(){
    scanf("%d",&n);
    For(i,1,2*n) scanf("%d",&a[i]);
    sort(a+1,a+2*n+1);
    int fir=1; *q=0;
    For(i,2,2*n+1)
        if (i==2*n+1||a[i]!=a[i-1]){
            q[++*q]=i-fir;
            fir=i;
        }
    For(i,0,*q) For(j,0,1) f[i][j]=0;
    f[0][0]=1; int S=0;
    For(i,1,*q){
        int nS=(S+q[i]);
        For(j,0,1) if (S%2||j==0)
            For(k,0,1) if (nS%2||k==0){
                int p1=(q[i]-S%2-nS%2)/2;
                if (S%2==1&&j==1) p1++;
                if (nS%2==1&&k==0) p1++;
                f[i][k]=(f[i][k]+1ll*f[i-1][j]*C(q[i],p1))%mo;
            }
        S=nS;
    }
    printf("%d\n",(f[*q][0]+f[*q][1])%mo);
}
int main(){
    init();
    int T;
    scanf("%d",&T);
    while (T--) solve();
}