[seqfan] Re: Planar distributive lattices

[Neil Sloane]

Allan, I confirm your numbers.  I'll run it through Superseeker, which will
tell us if it is a simple cousin of an existing entry, and if it doesn;t
find anything I will add it - it will be A343161.

Thanks for catching this fish!

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 Sat, Apr 17, 2021 at 9:22 PM Allan Wechsler <acwacw at gmail.com> wrote:

> I forget how I stumbled on this:
>
> https://math.chapman.edu/~jipsen/mathposters/Planar%20distributive%20lattices%20up%20to%20size%2011.pdf
> .
>
> It is a chart purporting to show all of the planar distributive lattices
> with up to 11 vertices. Like any true-hearted sequence fanatic I counted
> the number of these guys of each order, and got the following sequence:
>
> 1,1,1,2,3,5,8,14,24,42,72...
>
> Imagine my surprise at finding this sequence missing from OEIS! The author
> is apparently Dr. Peter Jipsen, at Chapman University in California.
>
> Perhaps someone here can figure out (a) what a planar distributive lattice
> is, (b) whether Dr. Jipsen enumerated them correctly, (c) whether I counted
> them off Jipsen's poster correctly, and (d) whether to add the sequence.
>
> Thank you!
>
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