Extension of Ned Gulley's wonderful Problem 317.
In a geometric series, ratio of adjacent elements is always a constant value. For example, [2 6 18 54] is a geometric series with a constant adjacent-element ratio of 3.
A vector will be given. Find the largest geometric series that can be formed from the vector.
Example:
input = [2 4 8 16 1000 2000]; output = [2 4 8 16];
Interesting problem but tests are too tricky.