[seqfan] Re: A195264

[Neil Sloane]

Hans,  Can you please tell me James Davis's address and email address?
 (There is a good chance I will see
John Conway this weekend.)

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 Tue, Jun 6, 2017 at 1:37 AM, Neil Sloane <njasloane at gmail.com> wrote:

> Dyslexics of the world, untie!
>
> J-P, Thank you!
>
> Now y=5 works, the prime is p = 96179,
> and (1407*10^5+1)*p = 13532385396179
> is indeed fixed by f !!!
>
>
> 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 <(732)%20828-6098>; home page: http://NeilSloane.com
> Email: njasloane at gmail.com
>
>
> On Tue, Jun 6, 2017 at 1:27 AM, jean-paul allouche <
> jean-paul.allouche at imj-prg.fr> wrote:
>
>> Dear Neil
>>
>> Is "1047" instead of "1407" a misprint in your email or in your search?
>> best wishes
>> jean-paul
>>
>> Le 06/06/17 à 07:25, Neil Sloane a écrit :
>>
>> I wish I understood that construction!  I can see he is looking
>>> for a number n = x*p which is fixed
>>> under our map f() = A080670(). Here p is a prime which is greater than
>>> any
>>> prime dividing x, so
>>> f(n) = f(x)*10^y + p,
>>> where y is the length of p.
>>> We want f(n) = n, so f(x)*10^y = p*(x-1),
>>> so
>>> 10^y*f(x)/(x-1) = p
>>>
>>> Now we are told that x = 1047*10^y + 1 is a good choice..
>>> But I didn't find any value of y (or p) that would work, so I must
>>> be missing something.
>>>
>>>
>>> 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 Mon, Jun 5, 2017 at 10:56 PM, Hans Havermann <gladhobo at bell.net>
>>> wrote:
>>>
>>> That's pretty amazing!  Where can one read more about James Davis's work?
>>>>>
>>>> He contacted me yesterday by way of a comment underneath my October 2014
>>>> blog on 'Climb to a Prime':
>>>>
>>>> http://gladhoboexpress.blogspot.ca/2014/10/climb-to-prime.html
>>>>
>>>> In a subsequent email he confided:
>>>>
>>>> "I'm not a mathematician by any stretch - the search that happened to
>>>> work
>>>> was hoping n = x*p=f(x)*10^y+p, where p is the largest prime factor of
>>>> n.
>>>> That requires that f(x)/(x-1) terminate and it's decimal expansion be a
>>>> prime (p). That motivates looking for x of the form x=m*10^y+1 and
>>>> hoping
>>>> some common factors cancel between f(x) and (x-1). Turned out to be
>>>> enough:
>>>> m=1407 fell out immediately."
>>>>
>>>>
>>>> --
>>>> Seqfan Mailing list - http://list.seqfan.eu/
>>>>
>>>> --
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>>>
>>
>>
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>
>