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Search: id:A102894
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| A102894 |
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Number of ACI algebras or semilattices on n generators, with no identity or annihilator. |
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+0
8
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OFFSET
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0,3
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COMMENT
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Or, number of families of subsets of {1, ..., n} that are closed under intersectionand contain both the universe and the empty set.
An ACI algebra or semilattice is a system with a single binary, idempotent, commutative and associative operation.
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REFERENCES
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G. Birkhoff, Lattice Theory. American Mathematical Society, Colloquium Publications, Vol. 25, 3rd ed., Providence, RI, 1967.
M. Habib and L. Nourine, The number of Moore families on n = 6, Discrete Math., 294 (2005), 291-296.
E. H. Moore, Introduction to a Form of General Analysis, AMS Colloquium Publication 2 (1910), pp. 53-80.
Maria Paola Bonacina and Nachum Dershowitz, Canonical Inference for Implicational Systems, in Automated Reasoning, Lecture Notes in Computer Science, Volume 5195/2008, Springer-Verlag.
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LINKS
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N. Dershowitz, G. S. Huang and M. Harris, Draft.
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FORMULA
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For asymptotics see A102897.
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CROSSREFS
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Cf. A102895, A102896, A102897, A108798, A108799, A108800, A108801.
Sequence in context: A126452 A082765 A132873 this_sequence A132552 A119729 A134110
Adjacent sequences: A102891 A102892 A102893 this_sequence A102895 A102896 A102897
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KEYWORD
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nonn,hard,more
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AUTHOR
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Mitch Harris (Harris.Mitchell(AT)mgh.harvard.edu), Jan 18 2005
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EXTENSIONS
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Additional comments from D. E. Knuth, Jul 01, 2005
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