A371868 Number of connected chordal bipartite graphs on n unlabeled vertices.

1, 1, 1, 3, 5, 16, 41, 154, 560, 2550, 12404, 69536, 428698, 2947229, 22288540, 185226859, 1682006569, 16635022967, 178525323313

Offset: 1

Author

Brendan McKay, Apr 09 2024

Keywords

• nonn
• hard
• more

Comments

A chordal bipartite graph is a bipartite graph with no induced cycles longer than 4-cycles. Note that this is not the same as a bipartite graph which is chordal, as that would exclude all cycles.

Examples

			The 3 examples for n=4 are the 4-cycle, the star, and the path.
		

Links

• Brendan McKay, nauty software that can generate these graphs.
• Wikipedia, Chordal bipartite graph.

Crossrefs

Cf. A371867, A371869.