MathDB
JBMO 2016 Problem 4

Source:

June 26, 2016
combinatorics

Problem Statement

A 5×55 \times 5 table is called regular f each of its cells contains one of four pairwise distinct real numbers,such that each of them occurs exactly one in every 2×22 \times 2 subtable.The sum of all numbers of a regular table is called the total sum of the table.With any four numbers,one constructs all possible regular tables,computes their total sums and counts the distinct outcomes.Determine the maximum possible count.