Problem A. 669. (April 2016)
A. 669. Determine whether the set of rational numbers can be ordered to in a sequence \(\displaystyle q_1,q_2,\ldots\) in such a way that there is no sequence of indices \(\displaystyle 1\le
i_1<i_2<\dots<i_6\) such that \(\displaystyle q_{i_1},q_{i_2},\ldots,q_{i_6}\) form an arithmetic progression.
Proposed by: Gyula Károlyi, Budajenő and Péter Komjáth, Budapest
(5 pont)
Deadline expired on May 10, 2016.
Statistics:
1 student sent a solution.  
2 points:  1 student. 
