A319490 Number of non-isomorphic connected graphs on n vertices with representation number 3.

0, 0, 0, 0, 0, 1, 39, 1852, 88838

Offset: 1

Author

Sergey Kitaev, Sep 20 2018

Keywords

• nonn
• more

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.

Examples

			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.
		

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.

Crossrefs

Cf. A319489 (graphs with representation number 2).