[seqfan] Re: A133579

[Neil Sloane]

A133058 needed  a similar correction (and lacks a b-file - Harvey?)

Best regards
Neil

Neil J. A. Sloane, President, OEIS Foundation.
11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
Phone: 732 828 6098; home page: http://NeilSloane.com
Email: njasloane at gmail.com


On Fri, Feb 13, 2015 at 9:13 PM, Neil Sloane <njasloane at gmail.com> wrote:

> First, about A133580: the definition was correct, and the terms were
> correct, but the offset should have been 0.  I changed the offset and added
> some example lines to clarify the situation.
>
> The b-file is now wrong, unfortunately (Harvey, could you correct it?),
> and probably the programs also need correcting.
>
> Following Franklin's hint, this suggests that the correct
> definition of A133579 should be:
>
> a(0)=a(1)=1; for n>1, a(n) = 3*a(n-1)  if a(n-1) and n are coprime,
> otherwise a(n) = a(n-1)/gcd(a(n-1),n).
>
> This almost matches the terms, but there is a mistake at
> a(6), I believe, - as Harvey noticed - so it
> needs to be recomputed. (a(6) should be 1 not 9). The offset is also wrong,
> it should be 0, and I will fix that.
>
> Best regards
> Neil
>
> Neil J. A. Sloane, President, OEIS Foundation.
> 11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
> Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
> Phone: 732 828 6098; home page: http://NeilSloane.com
> Email: njasloane at gmail.com
>
>
> On Fri, Feb 13, 2015 at 8:33 PM, Frank Adams-Watters <
> franktaw at netscape.net> wrote:
>
>> The definition is clearly wrong, since gcd(n,a(n-1)) always divides
>> a(n-1).
>>
>> A133580 seems to be related, and may provide a clue. (BTW, the offset for
>> A133580 is wrong; from the definition it should be 0.)
>>
>> Franklin T. Adams-Watters
>>
>>
>> -----Original Message-----
>> From: Harvey P. Dale <hpd at hpdale.org>
>> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
>> Sent: Fri, Feb 13, 2015 6:59 pm
>> Subject: [seqfan] A133579
>>
>>
>>         I cannot figure out how to generate the terms of the above
>> sequence from its
>> definition.
>>         Best,
>>         Harvey
>>
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>
>