from collections import defaultdict
from bisect import bisect_right


class PrefixMax:
    def __init__(self, xs: list[tuple[int, int]]):
        # tuple[key, val] : key でソートし、prefix max を求める
        # key   : 3 10 20
        # val   : 2  5  4
        # prmax : 2  5  5
        keys = []
        vals = []
        for k, v in sorted(xs):
            keys.append(k)
            vals.append(v)
        for i in range(1, len(vals)):
            vals[i] = max(vals[i], vals[i-1])

        self.keys = keys
        self.vals = vals

    def le(self, p: int, default):
        """インデックス p 以下の prefix max を求める"""
        s = bisect_right(self.keys, p)
        if s == 0:
            return default

        return self.vals[s-1]


def solve():
    N = int(input())
    A = list(map(int, input().split()))

    def f(xs: list[int]) -> list[int]:
        dp = [defaultdict(int) for _ in range(N)]

        prmaxes = []
        res = [1] * N
        for i in range(N):
            for j in range(i+1):
                d = xs[i] - xs[j]
                if d <= 0: continue

                # xs[j], xs[i] の長さ 2 の数列からスタート
                dp[i][d] = max(dp[i][d], 2)

                # 前の結果から伸ばす
                # for pd, plen in dp[j].items():
                #     if pd < d:
                #         dp[i][d] = max(dp[i][d], plen + 1)
                max_len = prmaxes[j].le(d-1, 0)
                dp[i][d] = max(dp[i][d], max_len + 1)

                res[i] = max(res[i], dp[i][d])

            prmaxes.append(PrefixMax(list(dp[i].items())))

        return res

    lefts = f(A)
    rights = f(A[::-1])[::-1]
    return max([a+b-1 for a, b in zip(lefts, rights)])


T = int(input())
for t in range(T):
    ans = solve()
    print(ans)