If I recall correctly, Andreescu & Andrica attributed the olympiad problem which prompted this question by S. Pek to the Russian magazine Kvant. Does anybody here know if the problem actually appeared in the pages of Kvant once?
Hope this question of mine doesn't get closed... I dared to ask it here because I believe that several MO users were avid readers of Kvant back in the day.
Thanks in advance for your attention!