A326223 Number of non-Hamiltonian unlabeled n-vertex digraphs (with loops).

1, 0, 7, 80, 2186

Offset: 0

Author

Gus Wiseman, Jun 15 2019

Keywords

• nonn
• more

Comments

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

Examples

			Non-isomorphic representatives of the a(2) = 7 digraph edge-sets:
  {}
  {11}
  {12}
  {11,12}
  {11,21}
  {11,22}
  {11,12,22}
		

Links

• Gus Wiseman, Non-isomorphic representatives of the a(3) = 80 non-Hamiltonian digraphs.

Crossrefs

The labeled case is A326220.

The case without loops is A326222.

The undirected case is A246446 (without loops) or A326239 (with loops).

Hamiltonian unlabeled digraphs are A326226.

Unlabeled digraphs not containing a Hamiltonian path are A326224.

Cf. A000595, A002416, A003087, A003216, A283420, A326204, A326218, A326225.