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%I #9 Aug 23 2023 08:43:16
%S 1,2,3,30,649
%N Number of unlabeled n-vertex digraphs (with loops) not containing a Hamiltonian path.
%C A directed path is Hamiltonian if it passes through every vertex exactly once.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Hamiltonian_path">Hamiltonian path</a>
%H Gus Wiseman, <a href="http://arxiv.org/abs/0709.0430">Enumeration of paths and cycles and e-coefficients of incomparability graphs</a>, arXiv:0709.0430 [math.CO], 2007.
%H Gus Wiseman, <a href="/A326224/a326224.png">Non-isomorphic representatives of the a(3) = 30 digraphs not containing a Hamiltonian path</a>.
%F A000595(n) = a(n) + A326221(n).
%Y The labeled case is A326213.
%Y The undirected case is A283420 (without loops).
%Y Unlabeled digraphs containing a Hamiltonian path are A326221.
%Y Unlabeled digraphs not containing a Hamiltonian cycle are A326223.
%Y Cf. A000595, A002416, A003087, A003216, A057864.
%K nonn,more
%O 0,2
%A _Gus Wiseman_, Jun 16 2019
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