MathDB
ARGENTINA MO 2023 Level 3 P1

Source:

March 20, 2024
rotationboardcombinatorics

Problem Statement

Let nn be a positive with n3n\geq 3. Consider a board of n×nn \times n boxes. In each step taken the colors of the 55 boxes that make up the figure bellow change color (black boxes change to white and white boxes change to black) The figure can be rotated 90°,180°90°, 180° or 270°270°. Firstly, all the boxes are white.Determine for what values of nn it can be achieved, through a series of steps, that all the squares on the board are black.