[seqfan] Re: Nice new sequence with interesting open problem

[Neil Sloane]

> Something is wrong with this sequence. 2 cannot follow 1. The definition
requires that 4 follow 1. Bob.

Bob,  I suspect you misread the definition.  There is nothing wrong!

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 Sun, Oct 6, 2019 at 8:41 PM <rgwv at rgwv.com> wrote:

> Something is wrong with this sequence. 2 cannot follow 1. The definition
> requires that 4 follow 1. Bob.
>
> -----Original Message-----
> From: SeqFan <seqfan-bounces at list.seqfan.eu> On Behalf Of Neil Sloane
> Sent: Thursday, September 12, 2019 1:20 PM
> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
> Subject: [seqfan] Nice new sequence with interesting open problem
>
> Sent in by Max Tohline
>
> A326344 a(1) = 1. Thereafter, if n is prime, a(n) is the next prime after
> a(n-1), but written backwards. If n is not prime, a(n) is the next
> composite after a(n-1), written backwards.
>
>
> 1, 2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 4, 5, 6, 8, 9, 11, 21, 32, 33, 43, 44,
> 74, 57, 85, 68, 96, 89, 79, 8, 11, 21, 22, 42, 44, 54, 95, 69, 7, 8, 11,
> 21, 32, 33, 43, 44, 74, 57, 85, 68, 96, 89, 79, 8, 9, 1, 4, 6, 7, 8, 11,
> 21, 22, 42, 44, 54, 95, 69, 7, 8, 11, 21, ...
>
>
> It appears that this does not exceed 909, reached for the first time at n =
> 21752
>
> Michel Marcus checked it up to 10^8.
>
> It would be nice to know more!
>
> The record high values are:
>
> 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 21, 32, 33, 43, 44, 74, 85, 96, 97, 98, 99,
> 101, 201, 202, 302, 703, 804, 806, 807, 808, 907, 908, 909 (as far as they
> are known, see A326298, A326402)
>
> Neil
>
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