Winning if it is divisible by p
Source: Kosovo TST 2020 Problem 2
February 8, 2020
number theoryprime numbers
Problem Statement
Let be an odd prime number. Ana and Ben are playing a game with alternate moves as follows: in each move, the player which has the turn choose a number, which was not choosen before by any of the player, from the set . This process continues until no number is left. After the end of the process, each player create the number by taking the product of the choosen numbers and then add 1. We say a player wins if the number that did create is divisible by , while the number that did create the opponent it is not divisible by , otherwise we say the game end in a draw. Ana start first move.
Does it exist a strategy for any of the player to win the game?Proposed by Dorlir Ahmeti, Kosovo