%I #7 Jun 16 2019 22:34:28

%S 1,0,7,80,2186

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

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

%H Gus Wiseman, <a href="/A326223/a326223_1.png">Non-isomorphic representatives of the a(3) = 80 non-Hamiltonian digraphs</a>.

%e Non-isomorphic representatives of the a(2) = 7 digraph edge-sets:

%e {}

%e {11}

%e {12}

%e {11,12}

%e {11,21}

%e {11,22}

%e {11,12,22}

%Y The labeled case is A326220.

%Y The case without loops is A326222.

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

%Y Hamiltonian unlabeled digraphs are A326226.

%Y Unlabeled digraphs not containing a Hamiltonian path are A326224.

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

%K nonn,more

%O 0,3

%A _Gus Wiseman_, Jun 15 2019