[seqfan] Re: Possible number of units in a ring

Max Alekseyev maxale at gmail.com
Mon Apr 23 08:49:52 CEST 2012

On Tue, Apr 17, 2012 at 12:16 PM, Charles Greathouse
<charles.greathouse at case.edu> wrote:
> Sequence A070932 is described in a comment:
> By considering the ring Z_n and the finite fields GF(q) this sequence
> contains the values of Euler function (A000010) and prime powers - 1 .
> By taking direct products if n and m belong to the sequence so is m*n.
> Do these conditions suffice to describe all terms of the sequence?

Probably not.
The first comment just gives examples of most "simple" rings. But
there exist more complicated rings.
Cf. A037289


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