MathDB
Pairwise LCMs greater than 4000

Source: SMO Senior 2019 Q3

June 29, 2019
number theoryleast common multiple

Problem Statement

Let a1,a2,,a2000a_1,a_2,\cdots,a_{2000} be distinct positive integers such that 1a1<a2<<a2000<40001 \leq a_1 < a_2 < \cdots < a_{2000} < 4000 such that the LCM (least common multiple) of any two of them is 4000\geq 4000. Show that a11334a_1 \geq 1334