MathDB
filling a 3xn table with numbers 1 to 3n, sum of rows and columns related

Source: Austria Beginners' Competition 2018 p3

February 24, 2020
combinatoricsSum

Problem Statement

For a given integer n4n \ge 4 we examine whether there exists a table with three rows and nn columns which can be filled by the numbers 1,2,...,,3n1, 2,...,, 3n such that \bullet each row totals to the same sum zz and \bullet each column totals to the same sum ss. Prove: (a) If nn is even, such a table does not exist. (b) If n=5n = 5, such a table does exist.
(Gerhard J. Woeginger)