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A319490
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Number of non-isomorphic connected graphs on n vertices with representation number 3.
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1
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OFFSET
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1,7
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COMMENTS
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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.
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LINKS
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EXAMPLE
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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.
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CROSSREFS
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Cf. A319489 (graphs with representation number 2).
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KEYWORD
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nonn,more
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AUTHOR
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STATUS
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approved
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