MathDB
The maximum number of 'allowed' set

Source: Middle European Mathematical Olympiad 2012 - Individuals I-2

September 14, 2012
floor functioncombinatorics proposedcombinatorics

Problem Statement

Let N N be a positive integer. A set S⊂{1,2,⋯ ,N} S \subset \{ 1, 2, \cdots, N \} is called allowed if it does not contain three distinct elements a,b,c a, b, c such that a a divides b b and b b divides cc. Determine the largest possible number of elements in an allowed set S S .
Back to ProblemsView on AoPS