#include<bits/stdc++.h>
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define REP(i,n) for(int i=(0);i<(n);i++)
#define fi first
#define se second
#define pb push_back
#define mp make_pair
using namespace std;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef long long ll;

template<class T> inline void read(T &x){
    int f=0;x=0;char ch=getchar();
    for(;!isdigit(ch);ch=getchar())f|=(ch=='-');
    for(;isdigit(ch);ch=getchar())x=x*10+ch-'0';
    if(f)x=-x;
}

const int mod=1e9+7;
const int N=2000005;
int a[N],fac[N],rev[N],n,ans;
map<int,int> cnt;

inline int power(int x,int p){
    int res=1;
    for(;p;p>>=1,x=(ll)x*x%mod)
        if(p&1)res=(ll)res*x%mod;
    return res;
}
inline int C(int n,int m){
    if(m<0||m>n)return 0;
    return (ll)fac[n]*rev[m]%mod*rev[n-m]%mod;
}

void MAIN(){
    cnt.clear();
    read(n);
    rep(i,1,2*n){
        read(a[i]);
        cnt[a[i]]++;
    }
    ans=1;
    int las=0;
    for(auto x:cnt){
        int t=x.se;
        if(las==0){
            ans=(ll)ans*C(t,t/2)%mod;
            if(t&1)ans=2*ans%mod;
        }
        else{
            if(t&1){
                ans=(ll)ans*C(t,t/2)%mod;
            }
            else{
                ans=(ll)ans*(C(t,t/2)+C(t,t/2-1))%mod;
            }
        }
        las^=t&1;
    }
    cout<<ans<<endl;
}

int main(){
    int lim=200000;
    fac[0]=1;
    rep(i,1,lim)
        fac[i]=(ll)fac[i-1]*i%mod;
    rev[lim]=power(fac[lim],mod-2);
    per(i,lim,1)
        rev[i-1]=(ll)rev[i]*i%mod;
    int T;
    read(T);
    while(T--)
        MAIN();
    
    return 0;
}