JBMO Shortlist 2021 N7
Source: JBMO Shortlist 2021
July 2, 2022
JuniorBalkanshortlist2021number theorygameexponential
Problem Statement
Alice chooses a prime number and then Bob chooses a positive integer . Alice, in the first move, chooses an integer and calculates the expression ; then Bob, in the second move, chooses an integer and calculates the expression ; etc. one by one. (Each player knows the numbers chosen by the other in the previous moves.) The winner is the one who first chooses the number such that divides . Who has a winning strategy?Proposed by Borche Joshevski, Macedonia