/************************************************

* Author        :Running_Time

* Created Time  :2015/11/1 14:58:49

* File Name     :J.cpp

 ************************************************/

#include <cstdio>

#include <algorithm>

#include <iostream>

#include <cstring>

#include <cmath>

#include <string>

#include <vector>

#include <queue>

#include <deque>

#include <stack>

#include <list>

#include <map>

#include <set>

#include <bitset>

#include <cstdlib>

#include <ctime>

using namespace std;

#define lson l, mid, rt << 1

#define rson mid + 1, r, rt << 1 | 1

typedef long long ll;

const int N = 1e3 + 10;

const int INF = 0x3f3f3f3f;

const int MOD = 1e9 + 7;

struct Trie {

    int ch[N*30][2], sz;

    int cnt[N*30];

    void init(void) {

        sz = 1; ch[0][0] = ch[0][1] = 0;

        memset (cnt, 0, sizeof (cnt));

    }

    void insert(int x)  {

        int u = 0;

        for (int c, i=30; i>=0; --i)   {

            c = x & (1 << i) ? 1 : 0;

            if (!ch[u][c])  {

                ch[sz][0] = ch[sz][1] = 0;

                ch[u][c] = sz++;

            }

            u = ch[u][c];

            cnt[u]++;

        }

    }

    void remove(int x)  {

        int u = 0;

        for (int c, i=30; i>=0; --i)    {

            c = x & (1 << i) ? 1 : 0;

            u = ch[u][c];

            cnt[u]--;

        }

    }

    int query(int x)    {

        int u = 0;

        for (int c, i=30; i>=0; --i)   {

            c = x & (1 << i) ? 1 : 0;

            if (c == 1) {

                if (ch[u][0] && cnt[ch[u][0]])  u = ch[u][0];

                else    u = ch[u][1], x ^= (1 << i);

            }

            else    {

                if (ch[u][1] && cnt[ch[u][1]])  u = ch[u][1], x ^= (1 << i);

                else    u = ch[u][0];

            }

        }

        return x;

    }

}trie;

int a[N];

int main(void)    {

    int T;  scanf ("%d", &T);

    while (T--) {

        int n;  scanf ("%d", &n);

        for (int i=1; i<=n; ++i)    {

            scanf ("%d", &a[i]);

        }

        int ans = 0;

        trie.init ();

        for (int i=1; i<=n; ++i)    {

            trie.insert (a[i]);

        }

        for (int i=1; i<=n; ++i)    {

            trie.remove (a[i]);

            for (int j=i+1; j<=n; ++j)  {

                trie.remove (a[j]);

                ans = max (ans, trie.query (a[i] + a[j]));

                trie.insert (a[j]);

            }

            trie.insert (a[i]);

        }

        printf ("%d\n", ans);

    }

    return 0;

}