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A238752 Number of nonisomorphic partial 1-differential posets up to rank n. 0
1, 1, 1, 1, 2, 5, 35, 643, 44606, 29199636 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

Table of n, a(n) for n=1..10.

P. Byrnes, Structural aspects of differential posets, Ph.D. thesis, University of Minnesota, (2012)

Richard P. Stanley, Fabrizio Zanello, On the rank function of a differential poset, arXiv:1111.4371 [math.CO], 2011-2012.

EXAMPLE

For n<=4, label nodes with the partitions of n for convenience.

At n=5, the two possible posets are the Young poset (nodes and covering relations are the partitions of 5) and the poset constructed by covering the partitions (31), (22) and (211) with a common element, then giving each of those partitions another cover, and leaving all other nodes the same.

CROSSREFS

Sequence in context: A063443 A133473 A193323 * A099137 A309667 A059586

Adjacent sequences:  A238749 A238750 A238751 * A238753 A238754 A238755

KEYWORD

nonn,more

AUTHOR

William J. Keith, Mar 04 2014

STATUS

approved

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Last modified October 15 22:25 EDT 2019. Contains 328038 sequences. (Running on oeis4.)