A361921 - OEIS

A361921

The number of unlabeled bounded Eulerian posets with n elements.

0, 1, 1, 0, 1, 0, 1, 0, 2, 0, 5, 0, 11

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,9

COMMENTS

A graded partially ordered set is Eulerian if every nontrivial interval has the same number of elements of even rank as of odd rank. It is bounded if it has a unique maximal and a unique minimal element.

LINKS

Table of n, a(n) for n=0..12.

Wikipedia, Eulerian poset

PROG

(Sage) sum(1 for P in posets(n-2) if (Q := P.with_bounds()).is_graded() and Q.is_eulerian())

CROSSREFS

Sequence in context: A242683 A242682 A281731 * A245928 A242839 A105523

Adjacent sequences: A361918 A361919 A361920 * A361922 A361923 A361924

KEYWORD

nonn,hard,more

AUTHOR

Martin Rubey, Mar 30 2023

STATUS

approved