A361955 Number of unlabeled connected weakly graded (ranked) posets with n elements.

1, 1, 1, 3, 10, 42, 202, 1146, 7493, 56996, 508609, 5414635, 70214227, 1134439731, 23331152887, 621768153861, 21761221300058, 1009759125475973, 62534859409597022, 5193886959561972984, 580677490292990902682, 87649885799470898359728, 17907726747155924589913398

Offset

0,4

Comments

Here weakly graded means that there exists a rank function rk from the poset to the integers such that whenever v covers w in the poset, we have rk(v) = rk(w) + 1.

Links

Andrew Howroyd, Table of n, a(n) for n = 0..40

Wikipedia, Graded poset.

Formula

Inverse Euler transform of A361920.

Prog

(PARI) \\ See PARI link in A361953 for program code.
A361955seq(20)

Crossrefs

Row sums of A361954.

Cf. A000608, A361920, A361953.

Sequence in context: A107594 A094195 A091843 * A300632 A300511 A007552

Adjacent sequences: A361952 A361953 A361954 * A361956 A361957 A361958

Keyword

nonn

Author

Andrew Howroyd, Mar 31 2023

Status

approved