On orders solely of abelian groups

Abstract

Let n = be the factorization of an integer n(>1) into prime powers, and set Φ(n):= . In particular, for squarefree n, Φ(n) = phi;(n). Consider the set.It is known (from [5]) that A consists precisely of those integers n for which there is no non-abelian group of order n. It is also known (from [7]) that the setconsists solely of integers n with the property that every group of order n is cyclic. We set C′ = A – C.