1,3

Or, free polysticks (polyedges) on the honeycomb net such that each stick belongs to at least one full hexagon, with n full hexagons. - Andrei Zabolotskii, Apr 03 2026

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]

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.

Lorentz Jäntschi, Topological Characterization of a Complete Set of Small‐Sized Graphene Sheets Using Molecular Descriptors With Energy Storage Applications, Ener. Stor. (2025) Vol. 7, Issue 6, Art No. e70253.

a(n) = A018190(n) + A038140(n) + A038141(n). - Andrei Zabolotskii, Feb 16 2023

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

nonn,more,changed

N. J. A. Sloane, Feb 09 2019

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

Name edited by Andrei Zabolotskii, Apr 03 2026

approved