C# code :

using System;

public class Solution { public static void Main(string[] args) { int t = Convert.ToInt32(Console.ReadLine());

    for (int i = 0; i < t; i++) {
        long n = Convert.ToInt64(Console.ReadLine());
        Console.WriteLine(PythagoreanTriplet(n));
    }
}

public static long PythagoreanTriplet(long n) {
    long result = -1;

    for (long k = 2; k <= n / 3; k++) {
        long j = ((n * n) - (2 * n * k)) / (2 * (n - k));
        long i = n - k - j;

        if (k * k + j * j == i * i) {
            result = Math.Max(result, k * j * i);
        }
    }

    return result;
}

}