

A319490


Number of nonisomorphic connected graphs on n vertices with representation number 3.


1




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



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).


KEYWORD

nonn,more


AUTHOR



STATUS

approved



