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.

(In reply to Corrected solution by Jer)

Your list agrees with mine; but there are 58 members on the list, not 57.

Posted by Charlie on 2013-02-28 12:50:23