[seqfan] Re: Concatenate the sums of the neighboring digits

[Frank Adams-watters]

We don't appear to have the concatenation of the products of the neighboring digits, though A035930 coincides for n <= 100.

Franklin T. Adams-Watters


-----Original Message-----
From: Neil Sloane <njasloane at gmail.com>
To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
Sent: Fri, Nov 1, 2019 1:19 pm
Subject: [seqfan] Re: Concatenate the sums of the neighboring digits

I created A328556 for the one-step function.
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, Nov 1, 2019 at 6:41 AM David Seal <david.j.seal at gwynmop.com> wrote:

> Another quick observation is that there are at least 9 loops other than
> the trivial one of the empty string of digits going to itself:
>
> 991 -> 1810 -> 991
> 992 -> 1811 -> 992
> 993 -> 1812 -> 993
> ...
> 999 -> 1818 -> 999
>
> The last of those is an exception to the "and grow" part of Hans's
> observation, though he may have meant "strictly inside".
>
> Also, longer strings of 9s with a single non-zero digit at the end are an
> example of growing forever 'non-chaotically' - i.e. in a way that is very
> easy to predict. For instance:
>
> 9991 -> 181810 -> 99991 -> 18181810 -> 9999991 -> 181818181810 ->
> 99999999991 -> ...
>
> has strings of 2+2^n 9s followed by a 1 growing to similar strings with n
> incremented by 1 every two generations.
>
> David
>
>
> > On 01 November 2019 at 04:27 Hans Havermann <gladhobo at bell.net> wrote:
> >
> >
> > Note that whenever three or more 9s find themselves adjacent inside a
> number, these segments will reproduce every second generation and grow.
> Continuing your 5677 example:
> >
> > ...
> > 786337
> > 15149610
> > 665131571
> > 12116446128
> > 3327108107310
> > 6598189171041
> > 11141799171088145
> > 22558161810881816959
> > 4710139779918169997151414
> >
> > The last one has three adjacent 9s so the sequence will grow forever.
> >
> > --
> > Seqfan Mailing list - http://list.seqfan.eu/
>
> --
> Seqfan Mailing list - http://list.seqfan.eu/
>

--
Seqfan Mailing list - http://list.seqfan.eu/