MathDB
Crickets on a number line

Source: Cono Sur 2010 #2

November 17, 2015
combinatoricscono sur

Problem Statement

On a line, 4444 points are marked and numbered 1,2,3,,441, 2, 3,…,44 from left to right. Various crickets jump around the line. Each starts at point 11, jumping on the marked points and ending up at point 4444. In addition, each cricket jumps from a marked point to another marked point with a greater number. When all the crickets have finished jumping, it turns out that for pair i,ji, j with 1i<j44{1}\leq{i}<{j}\leq{44}, there was a cricket that jumped directly from point ii to point jj, without visiting any of the points in between the two. Determine the smallest number of crickets such that this is possible.