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A058108
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Triangle read by rows: number of nonisomorphic semigroups of order n with k idempotents.
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8
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1, 2, 3, 5, 9, 10, 20, 50, 72, 46, 171, 309, 590, 594, 251, 5284, 2806, 5422, 7772, 5668, 1682, 1224331, 58583, 61323, 101539, 109107, 59576, 13213, 3667785000, 9207430, 1150085, 1466691, 1983558, 1626956, 690871, 119826, 105952488687468, 25412267163, 136799017, 27690828, 36991211, 39865274, 25666762, 8739857, 1228712
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OFFSET
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1,2
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LINKS
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Table of n, a(n) for n=1..45.
Andreas Distler, Classification and Enumeration of Finite Semigroups, A Thesis Submitted for the Degree of PhD, University of St Andrews (2010).
A. Distler and T. Kelsey, The semigroups of order 9 and their automorphism groups, arXiv preprint arXiv:1301.6023, 2013.
Index entries for sequences related to semigroups
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EXAMPLE
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1; 2,3; 5,9,10; 20,50,72,46; 171,309,590,594,251; ...
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CROSSREFS
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Row sums give A027851. Main diagonal: A058112. Columns 1-3: A058109-A058111.
Sequence in context: A057254 A057242 A090845 * A174512 A056144 A186776
Adjacent sequences: A058105 A058106 A058107 * A058109 A058110 A058111
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KEYWORD
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nonn,tabl,hard
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AUTHOR
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Christian G. Bower, Nov 09 2000
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EXTENSIONS
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Updated Feb 19 2001
More terms from Andreas Distler, Jan 13 2011
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STATUS
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approved
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