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%I A121220 #20 Jun 07 2021 09:30:02
%S A121220 1,3,11,44,186,813,3640,16590,76663,358195,1688784,8022273,38351973,
%T A121220 184353219,890371070,4318095442,21018564402,102642526470,502709028125,
%U A121220 2468566918644,12150769362815,59937663454017
%N A121220 Number of fixed hexagonal polygons (or benzenoids) with n cells.
%H A121220 Vaclav Kotesovec, <a href="/A121220/b121220.txt">Table of n, a(n) for n = 1..50</a> (terms 1..46 from N. J. A. Sloane) [all terms from Jensen link]
%H A121220 I. Jensen, <a href="https://web.archive.org/web/20160102114308/http://www.ms.unimelb.edu.au/~iwan/polygons/series/hc.area.ser">First 46 terms</a>
%H A121220 Iwan Jensen, <a href="http://arxiv.org/abs/0808.0963">A parallel algorithm for the enumeration of benzenoid hydrocarbons</a>, arXiv:0808.0963v1 [cond-mat.stat-mech], 2007-2008.
%H A121220 Markus Vöge, Anthony J. Guttmann, and Iwan Jensen, <a href="https://doi.org/10.1021/ci010098g">On the Number of Benzenoid Hydrocarbons</a>, Journal of Chemical Information and Computer Sciences, 42(3) (2002), 456-466. See Table 2 under the B_h column on page 462.
%F A121220 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).
%Y A121220 Cf. A018190.
%K A121220 nonn
%O A121220 1,2
%A A121220 _Parthasarathy Nambi_, Aug 20 2006
%E A121220 More terms from _N. J. A. Sloane_, Aug 25 2006

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