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A038142
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Number of planar cata-polyhexes with n cells.
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6
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1, 1, 2, 5, 12, 36, 118, 411, 1489, 5572, 21115
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OFFSET
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1,3
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COMMENTS
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Number of cata-condensed benzenoid hydrocarbons with n hexagons.
a(n) is the number of n-celled polyhexes with perimeter 4n+2. 4n+2 is the maximal perimeter of an n-celled polyhex. a(n) is the number of n-celled 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
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REFERENCES
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J. V. Knop et al., On the total number of polyhexes, Match, No. 16 (1984), 119-134.
N. Trinajstich, Z. Jerievi, J. V. Knop, W. R. Muller and K. Szymanski, COMPUTER GENERATION OF ISOMERIC STRUCTURES, Pure & Appl. Chem., Vol. 55, No. 2, pp. 379-39O, 1983.
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LINKS
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Table of n, a(n) for n=1..11.
Eric Weisstein's World of Mathematics, Polyhex.
Isoperimetrical Polyhexes
Poly Pages
Eric Weisstein's World of Mathematics, Fusene
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CROSSREFS
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Cf. A018190, A038143.
a(n) <= A000228(n), a(n) <= A057779(2n+1).
Sequence in context: A032203 A197444 A094717 * A052302 A009598 A002216
Adjacent sequences: A038139 A038140 A038141 * A038143 A038144 A038145
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane.
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EXTENSIONS
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a(11) from Tanya Khovanova, Jul 27 2007
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STATUS
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approved
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