

A038142


Number of planar catapolyhexes with n cells.


10



1, 1, 2, 5, 12, 36, 118, 411, 1489, 5572, 21115, 81121, 314075, 1224528, 4799205
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OFFSET

1,3


COMMENTS

Number of catacondensed benzenoid hydrocarbons with n hexagons.
a(n) is the number of ncelled polyhexes with perimeter 4n+2. 4n+2 is the maximal perimeter of an ncelled polyhex. a(n) is the number of ncelled polyhexes that have a tree as their connectedness graph (vertices of this graph correspond to cells and two vertices are connected if the corresponding cells have a common edge).  Tanya Khovanova, Jul 27 2007


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

Eric Weisstein's World of Mathematics, Polyhex.
Eric Weisstein's World of Mathematics, Fusene.


FORMULA



CROSSREFS



KEYWORD

nonn,hard,more


AUTHOR



EXTENSIONS



STATUS

approved



