A323930 Polycyclic aromatic hydrocarbons (for precise definition see He and He, 1986).

1, 1, 3, 7, 22, 81, 331, 1436, 6510, 30129, 141512, 671538, 3210620, 15443871, 74662005, 362506902

Offset

1,3

References

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]

Links

Table of n, a(n) for n=1..16.

Björg N. Cyvin, Jon Brunvoll and Sven J. Cyvin, Enumeration of benzenoid systems and other polyhexes, p. 65-180 in: I. Gutman (ed.), Advances in the Theory of Benzenoid Hydrocarbons II, Springer, 1992.

Wenchen He and Wenjie He, Generation and enumeration of planar polycyclic aromatic hydrocarbons, Tetrahedron 42.19 (1986): 5291-5299. See Table 1.

Formula

a(n) = A018190(n) + A038140(n) + A038141(n). - Andrey Zabolotskiy, Feb 16 2023

Crossrefs

Cf. A003104, A323923-A323929.

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

Cf. A038140, A038141.

Sequence in context: A111772 A233005 A018190 * A187982 A000228 A108070

Adjacent sequences: A323927 A323928 A323929 * A323931 A323932 A323933

Keyword

nonn,more

Author

N. J. A. Sloane, Feb 09 2019

Extensions

a(10)-a(16) from Cyvin, Brunvoll & Cyvin (Table 1) added by Andrey Zabolotskiy, Feb 08 2023

Status

approved