A326225 - OEIS

A326225

Number of Hamiltonian unlabeled n-vertex digraphs (without loops).

0, 1, 1, 4, 61, 3725, 844141, 626078904

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OFFSET

0,4

COMMENTS

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

LINKS

EXAMPLE

Non-isomorphic representatives of the a(3) = 4 digraph edge-sets:

{12,23,31}

{12,13,21,32}

{12,13,21,23,31}

{12,13,21,23,31,32}

CROSSREFS

The labeled case is A326219.

The case with loops is A326226.

The undirected case is A003216.

Non-Hamiltonian unlabeled digraphs (without loops) are A326222.

KEYWORD

nonn,hard,more

AUTHOR

Gus Wiseman, Jun 15 2019

EXTENSIONS

a(5)-a(7) from Sean A. Irvine, Jun 16 2019

STATUS

approved