This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A326224 #9 Aug 23 2023 08:43:16 %S A326224 1,2,3,30,649 %N A326224 Number of unlabeled n-vertex digraphs (with loops) not containing a Hamiltonian path. %C A326224 A directed path is Hamiltonian if it passes through every vertex exactly once. %H A326224 Wikipedia, <a href="https://en.wikipedia.org/wiki/Hamiltonian_path">Hamiltonian path</a> %H A326224 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 A326224 Gus Wiseman, <a href="/A326224/a326224.png">Non-isomorphic representatives of the a(3) = 30 digraphs not containing a Hamiltonian path</a>. %F A326224 A000595(n) = a(n) + A326221(n). %Y A326224 The labeled case is A326213. %Y A326224 The undirected case is A283420 (without loops). %Y A326224 Unlabeled digraphs containing a Hamiltonian path are A326221. %Y A326224 Unlabeled digraphs not containing a Hamiltonian cycle are A326223. %Y A326224 Cf. A000595, A002416, A003087, A003216, A057864. %K A326224 nonn,more %O A326224 0,2 %A A326224 _Gus Wiseman_, Jun 16 2019