[seqfan] Planar distributive lattices

Allan Wechsler acwacw at gmail.com
Thu Apr 15 03:08:03 CEST 2021

I forget how I stumbled on this:

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:


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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