MathDB
rows are DERANGED and a SOCOURGE to usajmo .

Source: USAJMO 2024/4

March 21, 2024
AMCUSA(J)MOUSAJMOJMO 2024 P4

Problem Statement

Let n3n \geq 3 be an integer. Rowan and Colin play a game on an n×nn \times n grid of squares, where each square is colored either red or blue. Rowan is allowed to permute the rows of the grid and Colin is allowed to permute the columns. A grid coloring is orderly if: [*]no matter how Rowan permutes the rows of the coloring, Colin can then permute the columns to restore the original grid coloring; and [*]no matter how Colin permutes the columns of the coloring, Rowan can then permute the rows to restore the original grid coloring. In terms of nn, how many orderly colorings are there?
Proposed by Alec Sun