Published online by Cambridge University Press: 20 November 2018
It is well known that if (n, ϕ(n)) = 1, where ϕ(n) denotes the Euler ϕ function, then the only group of order n is the cyclic group. This is a special case of a more general result due to Dickson (2, p. 201); namely, if
where the pi are distinct primes and each αi > 0, the necessary and sufficient conditions that the only groups of order n are abelian are (1) each αi ≤ 2 and (2) no
is divisible by any p1 … , ps.
We wish to establish a theorem which includes these two results. We let G(n) equal the number of groups of order n where
and we seek necessary and sufficient conditions on n so that
Clearly, this problem is equivalent to finding necessary and sufficient conditions on n so that all existing groups of order n be nilpotent.