MathDB
2016 Guts #22

Source:

August 14, 2022
2016Guts Round

Problem Statement

An n×nn\times n Latin square is a n×nn\times n grid that is filled with nn 11's, nn 22's, \dots, and nn nn's such that each column and row of the grid contains exactly one of each 11, 22, \dots, nn. For example, the following is a valid 2×22\times2 Latin square: [2112]\textstyle\begin{bmatrix}2&1\\1&2\end{bmatrix}, but this is not: [2121]\textstyle\begin{bmatrix}2&1\\2&1\end{bmatrix}. How many 4×44\times4 Latin squares are there?