/*
*/
#include<bits/stdc++.h>
using namespace std;
#define int long long
#define sqrt(a) sqrtl(a)
#define abs(a) llabs(a)
#define pow(a) powl(a)
typedef  pair<int,int> pi ;
#define if1(x) for(int i =1 ;i<=x;i++)
#define if0(x) for(int i = 0;i<x;i++)
#define jf0(x) for(int j = 0;j<x;j++)
#define jf1(x) for(int j = 1;j<=x;j++)
#define pb push_back
const int mod = 1e9+7;
const int inf = 0x3f3f3f3f;
const int N = 2e5+10;
void solve(){
    int m,n;
    cin>>n;
    map<int,int> mp;
    int ans = 0;
    vector<int> num;
    vector<pi> maxx(2);
    if0(n){
        cin>>m;
        num.push_back(m);
        mp[m]++;
        if(mp[m] > maxx[0].second){
            maxx[1] = maxx[0];
            maxx[0] = {m,mp[m]};
            ans =  max(ans,maxx[0].second | maxx[1].second);
        }
        else if(mp[m] >maxx[1].second){
            maxx[1] = {m,mp[m]};
            ans =  max(ans,maxx[0].second | maxx[1].second);
        }
    }
    // mp.clear();
    // maxx[0] = maxx[1] = {0,0};
    // for(int i = n-1;i>=0;i--){  
    //     m = num[i];
    //     mp[m]++;
    //     if(mp[m] > maxx[0].second){
    //         maxx[1] = maxx[0];
    //         maxx[0] = {m,mp[m]};
    //         ans =  max(ans,maxx[0].second | maxx[1].second);
    //     }
    //     else if(mp[m] >maxx[1].second){
    //         maxx[1] = {m,mp[m]};
    //         ans =  max(ans,maxx[0].second | maxx[1].second);
    //     }
    // }


    cout<<ans<<endl;
}
signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr); 
    int t=1;
    cin>>t;
    while (t--)
    {
        solve();
    }
    return 0;
}
/*


*/