MathDB

1

Part of 2020 Mediterranean Mathematics Olympiad

Problems(1)

gcd(m,n)=d and gcd(m,4n+1)=1

Source: Mediterranean Mathematical Olympiad 2020 P1 MMC

9/23/2020
Determine all integers m≥2m\ge2 for which there exists an integer n≥1n\ge1 with gcd⁡(m,n)=d\gcd(m,n)=d and gcd⁡(m,4n+1)=1\gcd(m,4n+1)=1.
Proposed by Gerhard Woeginger, Austria
number theorygreatest common divisor