MathDB
poor pigeon's egg got eaten by seagull

Source: 2022 IMOC C1

September 5, 2022
combinatoricsIMOC

Problem Statement

Given a positive integer kk, a pigeon and a seagull play a game on an n×nn\times n board. The pigeon goes first, and they take turns doing the operations. The pigeon will choose mm grids and lay an egg in each grid he chooses. The seagull will choose a k×kk\times k grids and eat all the eggs inside them. If at any point every grid in the n×nn\times n board has an egg in it, then the pigeon wins. Else, the seagull wins. For every integer nkn\geq k, find all mm such that the pigeon wins.
Proposed by amano_hina