Can you create a subset of (1, 2, 3, ..., 3k) such that none of its 2k-1 members is twice the value of another?

Either provide such a set or show none exists.

Inspired by: Austrian-Polish Math. Competition.

(In reply to re(2): Idea, no proof by Jer)

Unless I am mistaken, for k=42, doesn't your method show that there are *more* than 2k-1 (in this case, 2k) members in the solution set?  It's easy to see your solution is correct.  Maybe the problem statement is incorrect?

Posted by Kenny M on 2022-05-02 15:22:59