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A003041
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Number of vacuously transitive relations on n nodes up to isomorphism.
(Formerly M1764)
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3
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OFFSET
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1,1
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COMMENTS
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A transitive relation is vacuously transitive if it does not contain any transitive triple, that is, three distinct ordered pairs (a,b), (b,c), (a,c). - Jukka Kohonen, Sep 17 2021
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REFERENCES
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N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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EXAMPLE
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a(2)=7: The seven relations are {}, {(1,1)}, {(1,1),(2,2)}, {(2,1)}, {(1,1),(2,1)}, {(1,1),(2,1),(2,2)} and {(2,1),(2,2)}. - Jukka Kohonen, Sep 17 2021
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CROSSREFS
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KEYWORD
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nonn,more
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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