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A244493
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Number of oriented (0, 1, 2)-factors of the Johnson graph J(n, 2).
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1
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OFFSET
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2,2
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COMMENTS
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From James East, Jul 13 2016: (Start)
a(5) and a(6) were calculated by James Mitchell using the GAP System Packages Semigroups (see link).
a(n) is also the number of minimal size all-idempotent generating sets for the singular part of the Brauer monoid (see East-Gray paper). (End)
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LINKS
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Table of n, a(n) for n=2..8.
J. East, R. D. Gray, Diagram monoids and Graham-Houghton graphs: idempotents and generating sets of ideals, arXiv:1404.2359 [math.GR], 2014.
GAP, Semigroups
Ronald Niles, C++ project on GitHub
Ronald Niles, Computation of A244493
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PROG
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(C++) See Niles link.
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CROSSREFS
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Sequence in context: A332126 A229579 A033289 * A221900 A229773 A193983
Adjacent sequences: A244490 A244491 A244492 * A244494 A244495 A244496
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KEYWORD
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nonn,more
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AUTHOR
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N. J. A. Sloane, Jul 05 2014
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EXTENSIONS
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Name clarified by James East, Jul 14 2016
a(6) corrected and a(7) added by Ronald Niles, Apr 21 2017
a(8) added by Ronald Niles, Jun 25 2017
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STATUS
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approved
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