A235604 Number of equivalence classes of lattices of subsets of the power set 2^[n].

1, 1, 1, 4, 50, 7443, 95239971

Offset

0,4

Comments

This is also the number of inequivalent atomic lattices on n atoms or inequivalent strict closure systems under T1 separation axiom on n elements. - Dmitry I. Ignatov, Sep 27 2022

Links

Table of n, a(n) for n=0..6.

Donald M. Davis, Enumerating lattices of subsets, arXiv preprint arXiv:1311.6664 [math.CO], 2013.

Dmitry I. Ignatov, On the Cryptomorphism between Davis' Subset Lattices, Atomic Lattices, and Closure Systems under T1 Separation Axiom, arXiv:2209.12256 [cs.DM], 2022.

Crossrefs

The number of inequivalent closure operators on a set of n elements where all singletons are closed is given in A355517.

The number of all strict closure operators is given in A102894.

For T_1 closure operators, see A334254.

Sequence in context: A327229 A231832 A193157 * A221477 A122464 A226375

Adjacent sequences: A235601 A235602 A235603 * A235605 A235606 A235607

Keyword

nonn,more,hard

Author

N. J. A. Sloane, Jan 21 2014

Extensions

a(5) from Andrew Weimholt, Jan 27 2014

a(6) from Dmitry I. Ignatov, Sep 27 2022

Status

approved