#include<bits/stdc++.h>  
using namespace std;
typedef long long ll;
#define ri register int
const int M=1000000007;
int n,t,i,a[200005],j,k,b[200005],u;
ll ans,p[200005],inv[200005],f[200005];
inline int read() {
    char ch = getchar(); int x = 0, f = 1;
    while(ch < '0' || ch > '9') {
        if(ch == '-') f = -1;
        ch = getchar();
    } while('0' <= ch && ch <= '9') {
        x = x * 10 + ch - '0';
        ch = getchar();
    } return x * f;
}
ll qpow(ll a,ll b)
{
    ll s=a,ans=1;
    while(b)
    {
        if(b&1)
            ans=ans*s%M;
        s=s*s%M;
        b>>=1;
    }
    return ans;
}
ll C(int a,int b)
{
    return p[a]*inv[b]%M*inv[a-b]%M;
}
int main()
{
    t=read();
    p[0]=inv[0]=1;
    for(i=1;i<=200000;i++)
    {
        inv[i]=inv[i-1]*qpow(i,M-2)%M;
        p[i]=p[i-1]*i%M;
    }
    while(t--)
    {
        n=read();
        for(i=1;i<=n*2;i++)
            a[i]=read();
        u=0;
        for(i=1;i<=n*2;)
        {
            for(j=i;j<=n*2&&a[i]==a[j];j++);
            b[++u]=j-i;
            i=j;
        }
        ans=1;
        for(i=1;i<=u;i++)
        {
            int s=0;
            for(j=i;j<=u;j++)
            {
                s+=b[j];
                if(s%2==0)
                    break;
            }
            if(i==j)
                ans=ans*C(b[i],b[i]/2)%M;
            else
            {
                f[i]=C(b[i],b[i]/2);
                for(k=i+1;k<j;k++)
                    f[k]=f[k-1]*(C(b[k],b[k]/2+1)+C(b[k],b[k]/2))%M;
                f[j]=f[j-1]*C(b[j],b[j]/2)%M;
                ans=ans*f[j]%M*2%M;
            }
            i=j;
        }
        printf("%I64d\n",(ans%M+M)%M);
    }
}