[seqfan] Re: FW: A100083

Robert Gerbicz robert.gerbicz at gmail.com
Wed Jun 12 00:06:02 CEST 2013

My submitted comment: If n is in the sequence and k|n then k is also in the
sequence. In the other direction if s and t is in the sequence and
gcd(s,t)=1 then n=s*t is also in the sequence. This gives that we need to
check only the primepowers, then we can easily build the rest of the
sequence. The primepowers in the sequence begins with: 2,4,8,31,373

ps. This can also speedup a naive search.

2013/6/11 Giovanni Resta <g.resta at iit.cnr.it>

> On 06/11/2013 09:33 PM, Harvey P. Dale wrote:
>>  That might suggest that the next term of the "reduced series" is
> either 4312999 (373 x 11563) or
> > perhaps 133702969 (31 x 373 x 11563).
> I've not reached these two values (I'm just at 3.3*10^6 and the program
> becomes slower and slower), but I've checked them directly and they do not
> seem to belong to the sequence.
> Giovanni
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