Math Prize 2021 Problem 18
Source:
September 19, 2021
Math Prize for Girls
Problem Statement
Let be the set of square-free positive integers less than or equal to 50. (A square-free number is an integer that is not divisible by a perfect square bigger than 1.) How many 3-element subsets of are there such that the greatest common divisor of all 3 numbers in is 1, but no pair of numbers in is relatively prime?