[seqfan] Re: Nonmembers of Range of Euler Phi Function
Max Alekseyev
maxale at gmail.com
Mon Sep 20 04:09:06 CEST 2010
On Sun, Sep 19, 2010 at 5:53 PM, Ray Chandler
<rayjchandler at sbcglobal.net> wrote:
>
>> Calculating up to n=17, I find that these numbers all have
>> the form 2^n * p, where p is 3, 7, 17, 19, 31, 47. It's not
>> clear what sequence p is.
>> Might be A064699
At least the next term 383 also belongs to A064699 - see below.
> Using phiinv function defined in Mma code for A006511, I confirm terms
> continue as Tony describes above at least through a(582)=2^582*47, where the
> process seems to hang.
That's because A040076(47)=583.
Actually, a(583) = 2^583 * 383 and
for n=583, 584, ..., A040076(383)-1=6392, we have a(n) = 2^n * 383.
Regards,
Max
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