Set of positive integers and coloring points in red
Source: 2023 Girls in Mathematics Tournament- Level B, Problem 3
October 29, 2023
combinatorics
Problem Statement
Let be a set not empty of positive integers and a segment with, initially, only points and colored by red. An operation consists of choosing two distinct points colored already by red and an integer, and painting in red the points of segment such that and . Find the least positive integer such exists a subset of such that, after a finite number of operations, we can paint in red the point in the segment defined by . Also, find the number of such subsets for such a value of .