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 A323930 #18 Aug 29 2025 11:15:32 %S A323930 1,1,3,7,22,81,331,1436,6510,30129,141512,671538,3210620,15443871, %T A323930 74662005,362506902 %N A323930 Polycyclic aromatic hydrocarbons (for precise definition see He and He, 1986). %D A323930 N. Trinajstić, S. Nikolić, J. V. Knop, W. R. Müller and K. Szymanski, Computational Chemical Graph Theory: Characterization, Enumeration, and Generation of Chemical Structures by Computer Methods, Ellis Horwood, 1991. [incorrectly gives a(12) = 671512 in Table 4.13] %H A323930 Björg N. Cyvin, Jon Brunvoll and Sven J. Cyvin, <a href="https://doi.org/10.1007/BFb0018563">Enumeration of benzenoid systems and other polyhexes</a>, p. 65-180 in: I. Gutman (ed.), Advances in the Theory of Benzenoid Hydrocarbons II, Springer, 1992. %H A323930 Wenchen He and Wenjie He, <a href="https://doi.org/10.1016/S0040-4020(01)82078-0">Generation and enumeration of planar polycyclic aromatic hydrocarbons</a>, Tetrahedron 42.19 (1986): 5291-5299. See Table 1. %H A323930 Lorentz Jäntschi, <a href="https://doi.org/10.1002/est2.70253">Topological Characterization of a Complete Set of Small‐Sized Graphene Sheets Using Molecular Descriptors With Energy Storage Applications</a>, Ener. Stor. (2025) Vol. 7, Issue 6, Art No. e70253. %F A323930 a(n) = A018190(n) + A038140(n) + A038141(n). - _Andrey Zabolotskiy_, Feb 16 2023 %Y A323930 Cf. A003104, A323923-A323929. %Y A323930 A018190 is a very similar sequence with (as He and He remark) a slightly different definition. Cf. A000228, A038147. %Y A323930 Cf. A038140, A038141. %K A323930 nonn,more,changed %O A323930 1,3 %A A323930 _N. J. A. Sloane_, Feb 09 2019 %E A323930 a(10)-a(16) from Cyvin, Brunvoll & Cyvin (Table 1) added by _Andrey Zabolotskiy_, Feb 08 2023