#include<stdio.h>

#include<iostream>

#include<algorithm>

#include<string>

#include<string.h>

#include<math.h>

#include<limits.h>

#include<time.h>

#include<stdlib.h>

#include<map>

#include<queue>

#include<set>

#include<stack>

#include<vector>

#define LL long long

using namespace std;

int a[1000005];

bool equal(int a1, int a2, int b1, int b2)

{

    int r1 = __gcd(a1, a2), r2 = __gcd(b1, b2);

    a1 /= r1;

    a2 /= r1;

    b1 /= r2;

    b2 /= r2;

    return a1 == b1 && a2 == b2;

}

int main()

{

    int T;

    while(~scanf("%d", &T))

    {

        while(T--)

        {

            int n;

            scanf("%d", &n);

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

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

            int ans = 1;

            int flag = 0;

            int res = 2;

            for(int i = 2; i <= n; i++)

            {

                if(!flag)

                {

                    res = 2;

                    flag = 1;

                    ans = max(res, ans);

                }

                else

                {

                    if(a[i] - a[i - 1] == a[i - 1] - a[i - 2])

                    {

                        res++;

                        ans = max(ans, res);

                    }

                    else

                    {

                        flag = 0;

                        i--;

                    }

                }

            }

            flag = 0;

            res = 2;

            for(int i = 2; i <= n; i++)

            {

                if(!flag)

                {

                    res = 2;

                    flag = 1;

                    ans = max(res, ans);

                }

                else

                {

                    if(equal(a[i], a[i - 1], a[i - 1], a[i - 2]))

                    {

                        res++;

                        ans = max(ans, res);

                    }

                    else

                    {

                        flag = 0;

                        i--;

                    }

                }

            }

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

        }

    }

    return 0;

}