#include<bits/stdc++.h>

using namespace std;
#define ll long long

const int N = 200005, P = 1000000007;
int T, n, fac[N], ifac[N];
int Pow(ll x, int y=P-2){
    int ans=1;
    for(; y; y>>=1, x=x*x%P) if(y&1) ans=ans*x%P;
    return ans;
}
int main() {
    fac[0]=1;
    for(int i=1; i<=200000; ++i) fac[i]=(ll)fac[i-1]*i%P;
    ifac[200000]=Pow(fac[200000]);
    for(int i=200000; i; --i) ifac[i-1]=(ll)ifac[i]*i%P;
    scanf("%d", &T);
    while(T--){
        scanf("%d", &n);
        int ans=1;
        for(int i=1, last=0, cnt=0; i<=(n<<1|1); ++i){
            int x=0;
            if(i<=n<<1) scanf("%d", &x);
            if(x==last) ++cnt;
            else{
                if((i-cnt)&1){
                    if(cnt&1)
                        ans=(ll)ans*fac[cnt]%P*ifac[cnt/2]%P*ifac[cnt/2+1]%P;
                    else
                        ans=(ll)ans*fac[cnt]%P*ifac[cnt/2]%P*ifac[cnt/2]%P;
                }
                else{
                    if(cnt&1)
                        ans=2ll*fac[cnt]*ifac[cnt/2]%P*ifac[cnt/2+1]%P*ans%P;
                    else
                        ans=((ll)fac[cnt]*ifac[cnt/2]%P*ifac[cnt/2]+(ll)fac[cnt]*ifac[cnt/2-1]%P*ifac[cnt/2+1])%P*ans%P;
                }
                cnt=1, last=x;
            }
        }
        printf("%d\n", ans);
    }
    return 0;
}