Weird knight move
Source: Lusophon Mathematical Olympiad 2021 Problem 2
December 19, 2021
Easy Combinatorics
Problem Statement
Esmeralda has created a special knight to play on quadrilateral boards that are identical to chessboards. If a knight is in a square then it can move to another square by moving 1 square in one direction and 3 squares in a perpendicular direction (which is a diagonal of a rectangle instead of like in chess). In this movement, it doesn't land on the squares between the beginning square and the final square it lands on.A trip of the length of the knight is a sequence of squares which are all distinct such that the knight starts at the square and for each from to it can use the movement described before to go from the square to the .Determine the greatest such that there exists a path of the knight with length on a board.