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?
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.