A058801 Number of connected vertically indecomposable partial lattices on n unlabeled nodes.

1, 2, 6, 25, 116, 625, 3757, 25140, 184511, 1473861, 12711339, 117598686, 1160399052, 12152333659, 134487937252, 1566878426731, 19154490559458

Offset: 2

Author

Christian G. Bower, Dec 28 2000

Keywords

• nonn
• hard

Comments

A partial lattice is a poset where every pair of points has a unique least upper (greatest lower) bound or has no upper (lower) bound.

Links

• N. J. A. Sloane, Transforms

Crossrefs

Cf. A006966.

Programs

Mathematica

A058800 = Cases[Import["https://oeis.org/A058800/b058800.txt", "Table"], {, }][[All, 2]];
(* EulerInvTransform is defined in A022562 *)
EulerInvTransform[Drop[A058800, 3]] // Rest (* Jean-François Alcover, May 10 2019, updated Mar 17 2020 *)

Formula

Inverse EULER transform of A058800(n+2).

Extensions

a(17)-a(18) (computed from A058800) from Jean-François Alcover, May 10 2019