A371867 Number of chordal bipartite graphs on n unlabeled vertices.

1, 2, 3, 7, 13, 34, 84, 270, 912, 3755, 17169, 90953, 538858, 3586559, 26459702, 215517278, 1925402918, 18785105127, 199301164172

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. This sequence includes disconnected graphs.

Examples

			For n=3, the three examples are the two disconnected graphs and the path.
		

Links

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

Crossrefs

Cf. A371868, A371869.