A238752 Number of nonisomorphic partial 1-differential posets up to rank n.

1, 1, 1, 1, 2, 5, 35, 643, 44606, 29199636

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: A133473 A350955 A193323 * A099137 A309667 A059586

Adjacent sequences: A238749 A238750 A238751 * A238753 A238754 A238755

Keyword

nonn,more

Author

William J. Keith, Mar 04 2014

Status

approved