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 A121220 Number of fixed hexagonal polygons (or benzenoids) with n cells. 1
 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; text; internal format)
 OFFSET 1,2 LINKS Vaclav Kotesovec, Table of n, a(n) for n = 1..50 (terms 1..46 from N. J. A. Sloane) [all terms from Jensen link] I. Jensen, First 46 terms Iwan Jensen, A parallel algorithm for the enumeration of benzenoid hydrocarbons, arXiv:0808.0963v1 [cond-mat.stat-mech], 2007-2008. Markus Vöge, Anthony J. Guttmann, and Iwan Jensen, On the Number of Benzenoid Hydrocarbons, Journal of Chemical Information and Computer Sciences, 42(3) (2002), 456-466. See Table 2 under the B_h column on page 462. 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). CROSSREFS Cf. A018190. Sequence in context: A061706 A167012 A167013 * A068091 A001207 A319156 Adjacent sequences: A121217 A121218 A121219 * A121221 A121222 A121223 KEYWORD nonn AUTHOR Parthasarathy Nambi, Aug 20 2006 EXTENSIONS More terms from N. J. A. Sloane, Aug 25 2006 STATUS approved

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Last modified December 1 14:52 EST 2022. Contains 358468 sequences. (Running on oeis4.)