Dedekind numbers or Dedekind's problem: number of monotone Boolean functions of n variables, number of antichains of subsets of an n-set, number of elements in a free distributive lattice on n generators, number of Sperner families.
2, 3, 6, 20, 168, 7581, 7828354, 2414682040998, 5613043722868755790778
4 seqfan posts
Sat Dec 4 13:07:56 CET 2010 [seqfan] Re: useless references?
Sat Dec 4 11:56:09 CET 2010 [seqfan] useless references?
Fri Oct 29 05:35:16 CEST 2010 [seqfan] Implementing first 500 sequences in Java
Tue Aug 10 13:40:39 CEST 2010 [seqfan] abstract simplicial complexes of same-dimensional facets
Index of A-numbers in seqfan: by ascending order
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