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Search: id:A023814
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| A023814 |
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Number of associative binary operations on an n-set; number of labeled semigroups. |
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+0 12
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OFFSET
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0,3
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LINKS
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Eric Postpischil Posting to sci.math newsgroup, May 21 1990
C. Noebauer, Home page
C. Noebauer, The Numbers of Small Rings
C. Noebauer, Thesis on the enumeration of near-rings
Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.
Index entries for sequences related to semigroups
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CROSSREFS
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Cf. A001423, A001426, A023813, A023815, A027851.
a(n)+A079172(n)=A002489(n)
Sequence in context: A072402 A092084 A099715 this_sequence A062126 A113670 A056988
Adjacent sequences: A023811 A023812 A023813 this_sequence A023815 A023816 A023817
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KEYWORD
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nonn
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AUTHOR
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Lyle Ramshaw (ramshaw(AT)pa.dec.com)
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