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Search: id:A027851
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| A027851 |
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Number of nonisomorphic semigroups of order n. |
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+0
16
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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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a(n)=A001423(n)*2-A029851(n). Cf. A001426, A023814, A058108.
a(n)+A079173(n)=A001329(n)
Sequence in context: A009424 A009601 A009676 this_sequence A120765 A051812 A003224
Adjacent sequences: A027848 A027849 A027850 this_sequence A027852 A027853 A027854
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KEYWORD
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nonn,hard,nice
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AUTHOR
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Christian G. Bower (bowerc(AT)usa.net), Dec 13 1997, updated Feb 19 2001
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