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A058123
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Triangle: semigroups of order n with k idempotents, considered to be equivalent when they are isomorphic or anti-isomorphic (by reversal of the operator).
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5
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1, 2, 2, 5, 7, 6, 19, 37, 44, 26, 132, 216, 351, 326, 135, 3107, 1780, 3093, 4157, 2961, 875, 623615, 32652, 33445, 53145, 56020, 30395, 6749, 1834861133, 4665709, 600027, 754315, 1007475, 822176, 348692, 60601, 52976551026562, 12710266442, 68769167, 14050493, 18660074, 20044250, 12889961, 4389418, 618111
(list; table; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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LINKS
| Andreas Distler, Classification and Enumeration of Finite Semigroups, A Thesis Submitted for the Degree of PhD, University of St Andrews (2010).
Index entries for sequences related to semigroups
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EXAMPLE
| 1; 2,2; 5,7,6; 19,37,44,26; 132,216,351,326,135; ...
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CROSSREFS
| Row sums give A001423. Main diagonal: A002788. Columns 1-3: A002787, A002788, A005591.
Sequence in context: A136536 A023507 A095674 * A035586 A188623 A097050
Adjacent sequences: A058120 A058121 A058122 * A058124 A058125 A058126
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KEYWORD
| nonn,tabl,hard
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AUTHOR
| Christian G. Bower (bowerc(AT)usa.net), Nov 10 2000
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EXTENSIONS
| More terms from Andreas Distler (andreas(AT)mcs.st-andrews.ac.uk), Jan 13 2011
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