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A003088
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Number of unilateral digraphs with n unlabeled nodes.
(Formerly M2011)
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6
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OFFSET
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0,3
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REFERENCES
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F. Harary and E. M. Palmer, Graphical Enumeration, Academic Press, NY, 1973, p. 218.
R. C. Read and R. J. Wilson, An Atlas of Graphs, Oxford, 1998.
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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CROSSREFS
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KEYWORD
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nonn,nice,more
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AUTHOR
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EXTENSIONS
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Note that Read and Wilson incorrectly give a(4) as 172 - thanks to Vladeta Jovovic, Goran Kilibarda for finding this error and for verifying a(5).
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STATUS
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approved
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