MathDB
Many gcd's and lcm's

Source: 2020 Iberoamerican #4

November 17, 2020
number theory

Problem Statement

Show that there exists a set C\mathcal{C} of 20202020 distinct, positive integers that satisfies simultaneously the following properties: \bullet When one computes the greatest common divisor of each pair of elements of C\mathcal{C}, one gets a list of numbers that are all distinct. \bullet When one computes the least common multiple of each pair of elements of C\mathcal{C}, one gets a list of numbers that are all distinct.