MathDB
Romania TST 2021 Day 1 P1

Source:

May 15, 2021
combinatoricsSetsRomanian TSTTST

Problem Statement

Let k>1k>1 be a positive integer. A set SS{} is called good if there exists a colouring of the positive integers with kk{} colours, such that no element from SS{} can be written as the sum of two distinct positive integers having the same colour. Find the greatest positive integer tt{} (in terms of kk{}) for which the set S={a+1,a+2,,a+t}S=\{a+1,a+2,\ldots,a+t\}is good, for any positive integer aa{}.