#include<iostream>
#include<cstdio>
#include<vector>
#include<bitset>
#define N 2000
#define mod 998244353
using namespace std;
const int inv2=(mod+1)>>1;
int read()
{
	char c=0;
	int sum=0;
	while (c<'0'||c>'9') c=getchar();
	while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
	return sum;
}
int MD(int x)
{
	return x>=mod?x-mod:x;
}
int MD2(int x)
{
	return x<0?x+mod:x;
}
void Adder(int &x,int d)
{
	x+=d;
	if (x>=mod) x-=mod;
	return;
}
void Adder2(int &x,int d)
{
	x+=d;
	if (x<0) x+=mod;
	return;
}
int T,n,length,ans,ans2,a[N+1],F[N+1];
bool used[N+1];
bitset<N+1>E[N+1];
vector<int>p[N+1];
vector<int>num[N+1];
int main()
{
	int l,r,l2,r2;
	F[0]=1;
	for (int i=1;i<=N;++i) F[i]=MD(F[i-1]+1ll*(i-1)*F[i-2]%mod);
	T=read();
	while (T--)
	{
		n=read(),ans=ans2=1,length=0;
		for (int i=1;i<=n;++i) p[i].clear();
		for (int i=1;i<=n;++i) a[i]=read(),p[a[i]].push_back(i);
		for (int i=1;i<=n;++i) ans=1ll*ans*F[p[i].size()]%mod;
		for (int i=1;i<=n;++i) used[i]=0,E[i].reset();
		for (int i=1;i<=n;++i)
		{
			num[i].resize(p[i].size());
			for (int j=0;j+1<p[i].size();++j) num[i][j]=++length;
		}
		for (int i=1;i<=n;++i)
			for (int j=i+1;j<=n;++j)
			{
				for (int k=0;k<p[i].size();++k)
					for (int t=0;t<p[j].size();++t)
						if (p[i][k]<p[j][t])
						{
							if (k+1==p[i].size()) l=0,r=k-1;
							else l=r=k;
							if (t+1==p[j].size()) l2=0,r2=t-1;
							else l2=r2=t;
							for (int s=l;s<=r;++s)
								for (int w=l2;w<=r2;++w)
									E[num[i][s]][num[j][w]].flip(),E[num[j][w]][num[i][s]].flip();
						}
			}
		for (int i=1;i<=length;++i)
			for (int j=i+1;j<=length;++j)
				if (!used[i]&&!used[j]&&E[i][j])
				{
					used[i]=used[j]=1,ans2=2ll*ans2%mod;
					if (E[i][i]&&E[j][j]) ans2=MD2(-ans2);
					for (int k=1;k<=length;++k)
						if (!used[k])
						{
							if (E[i][i]&&E[i][k]) E[k][k].flip();
							if (E[j][j]&&E[j][k]) E[k][k].flip();
							if (E[i][k]) E[k]^=E[j];
							if (E[j][k]) E[k]^=E[i];
							if (E[i][k]&&E[j][k]) E[k][k].flip();
					    }
				}
		for (int i=1;i<=length;++i)
			if (!used[i])
			{
				if (E[i][i]) ans2=0;
				else ans2=2ll*ans2%mod;
			}
		printf("%lld\n",1ll*(ans+ans2)*inv2%mod);
	}
	return 0;
}