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

1,2

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.

Links

Table of n, a(n) for n=1..19.

Brendan McKay, nauty software that can generate these graphs.

Wikipedia, Chordal bipartite graph.

Example

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

Crossrefs

Cf. A371868, A371869.

Sequence in context: A129859 A280765 A056953 * A321681 A045611 A006840

Adjacent sequences: A371864 A371865 A371866 * A371868 A371869 A371870

Keyword

nonn,hard,more

Author

Brendan McKay, Apr 09 2024

Status

approved