A108071 Number of inner dual graphs of planar polyhexes with n hexagons.

1, 1, 2, 4, 8, 21, 53, 151, 458, 1477, 4918, 16956, 59494, 212364, 766753, 2796876, 10284793, 38096072, 141998218, 532301941, 2005638293, 7592441954, 28865031086, 110174528925, 422064799013, 1622379252093

Offset

1,3

Links

Table of n, a(n) for n=1..26.

Gunnar Brinkmann, Gilles Caporossi and Pierre Hansen, A constructive enumeration of fusenes and benzenoids, Journal of Algorithms, Volume 45, Issue 2, November 2002, Pages 155-166.

Gunnar Brinkmann, Gilles Caporossi and Pierre Hansen, A Survey and New Results on Computer Enumeration of Polyhex and Fusene Hydrocarbons, J. Chem. Inf. Comput. Sci. 2003, 43, 3, 842-851.

Example

For n = 4, the a(n) = 4 graphs are: the 4-path, which is the inner dual of 4 polyhexes out of A018190(4) = 7 (each of the others is an inner dual of a single polyhex); the paw graph; the diamond graph; the claw graph.

Crossrefs

Cf. A018190, A108070, A108072.

Sequence in context: A216643 A002040 A162110 * A337762 A055876 A065847

Adjacent sequences: A108068 A108069 A108070 * A108072 A108073 A108074

Keyword

nonn

Author

Gunnar Brinkmann, Jun 05 2005

Extensions

Name corrected by Andrey Zabolotskiy, Oct 01 2022

Status

approved