Find nine different integers from 1 to 20 inclusive such that no combination of any three of the nine integers form an arithmetic sequence.

(For example, if two of the integers chosen were 7 and 13, then that would preclude 1, 10 and 19 from being included.)

(In reply to re(4): Counting Up,,,,Why not up and down? by Charlie)

i fully get your point.

No claim was made on a method , and I  have only esplained how I got it , not how to  evaluate k out of m members.

No doubt, for larger numbers a similar problem needs computerized method.

Posted by Ady TZIDON on 2013-04-09 09:35:44