 Reduced residue system

A **reduced residue system** is a set of integers that are representatives of the distinct equivalence classes of integers modulo \( n \), where \( n \) is a positive integer, and each representative in the set is coprime to \( n \). In other words, a reduced residue system modulo \( n \) consists of integers that are both less than \( n \) and relatively prime to \( n \).