Question 10
How many ways are there to select four distinct integers a, b, c and d from 1, 2, ... ,600 such that a, b, c and d forms a strictly increasing geometric sequence whose common ratio is positive integer? Note: Two examples of a geometric sequence are 1, 2, 4, 8, 16, ... having a common ratio of 2 and 2, 6, 18, 54, 162, ... having a common ratio of 3.