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 A326221 #8 Aug 23 2023 08:43:21 %S A326221 0,0,7,74,2395 %N A326221 Number of unlabeled n-vertex digraphs (with loops) containing a Hamiltonian path. %C A326221 A directed path is Hamiltonian if it passes through every vertex exactly once. %H A326221 Wikipedia, <a href="https://en.wikipedia.org/wiki/Hamiltonian_path">Hamiltonian path</a> %H A326221 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 A326221 Gus Wiseman, <a href="/A326221/a326221.png">Non-isomorphic representatives of the a(3) = 74 digraphs containing a Hamiltonian path</a>. %F A326221 A000595(n) = a(n) + A326224(n). %Y A326221 The labeled case is A326214. %Y A326221 The undirected case is A057864 (without loops). %Y A326221 Unlabeled digraphs not containing a Hamiltonian path are A326224. %Y A326221 Unlabeled digraphs containing a Hamiltonian cycle are A326226. %Y A326221 Cf. A000595, A002416, A003087, A003216, A283420. %K A326221 nonn,more %O A326221 0,3 %A A326221 _Gus Wiseman_, Jun 16 2019