Problem

Source: ToT - 2001 Fall Junior A-Level #1

Tags: greatest common divisor, number theory unsolved, number theory



Do there exist postive integers $a_1<a_2<\cdots<a_{100}$ such that for $2\le k\le100$ the greatest common divisor of $a_{k-1}$ and $a_k$ is greater than the greatest common divisor of $a_k$ and $a_{k+1}$?