Three positive integers are chosen at random without replacement from 1,2,....,64. What is the probability that the numbers chosen are in geometric sequence?

Order of choice doesn't matter. For example, 4-1-2 would qualify as numbers in geometric sequence.

Bonus Question:
Generalise this result (in terms of n) covering the situation where three positive integers are chosen at random without replacement from 1,2,.....,n².

p=54/41664=0.001296   ....edited

Edited on February 28, 2013, 3:36 pm

Posted by Ady TZIDON on 2013-02-28 10:51:53