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 A319490 Number of non-isomorphic connected graphs on n vertices with representation number 3. 1
 0, 0, 0, 0, 0, 1, 39, 1852, 88838 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,7 COMMENTS These are graphs that can be represented by words having three copies of each letter, but cannot be represented by words having two copies of each letter. In a word representing a graph G, letters x and y alternate if any only if there is an edge between x and y in G. LINKS Ozgur Akgun, Ian P. Gent, Sergey Kitaev, Hans Zantema, Solving computational problems in the theory of word-representable graphs, arXiv:1808.01215 [math.CO], 2018. Sergey Kitaev, A comprehensive introduction to the theory of word-representable graphs, arXiv:1705.05924 [math.CO], 2017. EXAMPLE The triangular prism is the only graph on 6 vertices that can be represented using three copies of each letter, but cannot be represented using 2 copies of each letter. CROSSREFS Cf. A319489 (graphs with representation number 2). Sequence in context: A269028 A158768 A139191 * A327589 A176073 A145619 Adjacent sequences:  A319487 A319488 A319489 * A319491 A319492 A319493 KEYWORD nonn,more AUTHOR Sergey Kitaev, Sep 20 2018 STATUS approved

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Last modified December 6 13:45 EST 2021. Contains 349563 sequences. (Running on oeis4.)