#include <bits/stdc++.h>

using namespace std;

const int MAXN = 2010;
const int mod = 1000000007;

int memo[MAXN][MAXN][2];
int bt(int a, int b, bool last) {
    if (a < 0 || b < 0) return 0;
    if (a == 0 && b == 0) return 1;
    if (memo[a][b][last] != -1) return memo[a][b][last];
    int &ret = memo[a][b][last];
    ret = 0;
    if (last) {
        ret += (1LL * (b - 1) * bt(a, b - 1, false) + 1LL * a * bt(a - 1, b + 1, true)) % mod;
        ret %= mod;
    }
    else {
        ret += (1LL * a * bt(a - 1, b + 1, true) + 1LL * b * bt(a, b - 1, false)) % mod;
        ret %= mod;
    }
    return ret;
}

int main() {
    memset(memo, -1, sizeof memo);
    int q;
    scanf("%d", &q);
    while (q--) {
        int n;
        scanf("%d", &n);
        int a = 0, b = 0;
        set<int> st;
        for (int i = 0; i < n; i++) {
            int x;
            scanf("%d", &x);
            if (st.count(x)) {
                a++;
            }
            else {
                st.insert(x);
            }
        }
        b = n - 2 * a;
        int ans = 1LL * bt(a, b, false);
        printf("%d\n", ans);
    }
}