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Polycyclic aromatic hydrocarbons (for precise definition see He and He, 1986).
8

%I #14 Feb 16 2023 14:59:05

%S 1,1,3,7,22,81,331,1436,6510,30129,141512,671538,3210620,15443871,

%T 74662005,362506902

%N Polycyclic aromatic hydrocarbons (for precise definition see He and He, 1986).

%D 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 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 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.

%F a(n) = A018190(n) + A038140(n) + A038141(n). - _Andrey Zabolotskiy_, Feb 16 2023

%Y Cf. A003104, A323923-A323929.

%Y A018190 is a very similar sequence with (as He and He remark) a slightly different definition. Cf. A000228, A038147.

%Y Cf. A038140, A038141.

%K nonn,more

%O 1,3

%A _N. J. A. Sloane_, Feb 09 2019

%E a(10)-a(16) from Cyvin, Brunvoll & Cyvin (Table 1) added by _Andrey Zabolotskiy_, Feb 08 2023