MathDB
set of primes is infinite

Source: IMOC 2018 C4

August 16, 2021
number theorycombinatorics

Problem Statement

For a sequence {ai}i1\{a_i\}_{i\ge1} consisting of only positive integers, prove that if for all different positive integers ii and jj, we have aiaja_i\nmid a_j, then {pp is a prime and pai for some i}\{p\mid p\text{ is a prime and }p\mid a_i\text{ for some }i\}is a infinite set.