A323851 Number of branched cata-condensed benzenoid hydrocarbons with n hexagons.

0, 0, 0, 1, 2, 12, 51, 229, 969, 4098, 16867, 68925, 278907, 1123302, 4507640, 18058217, 72282999, 289346082, 1158844653, 4645422984, 18642827557, 74911194797, 301411059620, 1214395257920

Offset

1,5

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.

Links

Table of n, a(n) for n=1..24.

A. T. Balaban, J. Brunvoll, B. N. Cyvin, and S. J. Cyvin, Enumeration of branched catacondensed benzenoid hydrocarbons and their numbers of Kekulé structures Tetrahedron, 44(1) (1988), 221-228. See Table 1.

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

Crossrefs

Cf. A003104, A038142, A323924-A323930.

Sequence in context: A012382 A198008 A359523 * A054667 A009537 A057547

Adjacent sequences: A323848 A323849 A323850 * A323852 A323853 A323854

Keyword

nonn,more

Author

N. J. A. Sloane, Feb 09 2019

Extensions

a(13)-a(15) from Trinajstić et al. (Table 4.2, the number of cata-condensed benzenoids with h hexagons, branched) added by Andrei Zabolotskii, Feb 08 2023

Name clarified, a(16)-a(24) added using data from A038142 by Andrei Zabolotskii, Apr 02 2026

Status

approved