MathDB
fill the n x n table with numbers 1, 2 and -3 so that each sum is 0

Source: Czech-Polish-Slovak Match Junior 2019, individual p3 CPSJ

January 20, 2020
combinatoricsnumbers in a table

Problem Statement

Determine all positive integers nn such that it is possible to fill the n×nn \times n table with numbers 1,21, 2 and 3-3 so that the sum of the numbers in each row and each column is 00.