A326215 Number of Hamiltonian unlabeled n-vertex graphs with loops.

0, 2, 0, 4, 20

Offset

0,2

Comments

A graph is Hamiltonian if it contains a cycle passing through every vertex exactly once.

Links

Table of n, a(n) for n=0..4.

Wikipedia, Hamiltonian path

Gus Wiseman, Non-isomorphic representatives of the a(4) = 20 Hamiltonian graphs with loops.

Example

Non-isomorphic representatives of the a(3) = 4 edge-sets:
  {12,13,23}
  {12,13,23,33}
  {12,13,22,23,33}
  {11,12,13,22,23,33}

Crossrefs

The labeled case is A326240.

The directed case is A326226 (with loops) or A326225 (without loops).

The case without loops A003216.

Cf. A000088, A006125, A057864, A283420, A326239.

Sequence in context: A317364 A265664 A320490 * A248643 A199852 A055978

Adjacent sequences: A326212 A326213 A326214 * A326216 A326217 A326218

Keyword

nonn,more

Author

Gus Wiseman, Jun 17 2019

Status

approved