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A121220
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Number of fixed hexagonal polygons (or benzenoids) with n cells.
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1
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1, 3, 11, 44, 186, 813, 3640, 16590, 76663, 358195, 1688784, 8022273, 38351973, 184353219, 890371070, 4318095442, 21018564402, 102642526470, 502709028125, 2468566918644, 12150769362815, 59937663454017
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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REFERENCES
| Iwan Jensen, A parallel algorithm for the enumeration of benzenoid hydrocarbons, arXiv:0808.0963v1 [cond-mat.stat-mech].
Markus Voege, Anthony J. Guttmann and Iwan Jensen, "On the number of benzenoid hydrocarbons", J. Chem. Inf. Comput. Sci., (2002), vol. 42, 456-466. See Table 2 under the B_h column on page 462.
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LINKS
| N. J. A. Sloane, Table of n, a(n) for n = 1..46 [from Jensen link]
I. Jensen, First 46 terms
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FORMULA
| See equation 11 on page 463 of the paper by Markus Voege, Anthony J. Guttmann and Iwan Jensen for an asymptotic form for a(n).
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CROSSREFS
| Cf. A018190.
Sequence in context: A061706 A167012 A167013 * A068091 A001207 A026887
Adjacent sequences: A121217 A121218 A121219 * A121221 A121222 A121223
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KEYWORD
| nonn
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AUTHOR
| Parthasarathy Nambi (PachaNambi(AT)yahoo.com), Aug 20 2006
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EXTENSIONS
| More terms from N. J. A. Sloane (njas(AT)research.att.com), Aug 25 2006
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