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%I #17 Nov 09 2023 12:48:55
%S 1,1,2,4,11,37,136,540,2229,9505
%N Number of polyhexes (without holes) of size 6*n+1 with 6-fold rotational symmetry.
%H Björg N. Cyvin, Jon Brunvoll and Sven J. Cyvin, <a href="https://doi.org/10.1007/BFb0018563">Enumeration of benzenoid systems and other polyhexes</a>, p. 65-180 in: I. Gutman (ed.), Advances in the Theory of Benzenoid Hydrocarbons II, Springer, 1992.
%H S. J. Cyvin, J. Brunvoll, and B. N. Cyvin, <a href="http://dx.doi.org/10.1016/0898-1221(89)90168-5">Topological aspects of benzenoids and coronoids, including "snowflakes" and "laceflowers"</a>, Computers & Mathematics with Applications, vol. 17, no. 1-3, pp. 355-374, (1989); see table 1 on p. 361.
%H S. J. Cyvin, B. N. Cyvin, and J. Brunvoll, <a href="http://dx.doi.org/10.1016/0022-2860(89)80027-4">Benzenoids with hexagonal symmetry, including the rare animals "all-flakes"</a>, Journal of Molecular Structure, vol. 198, pp. 31-49, (July 1989); see p. 32 for images of all such polyhexes for 6*n+1 <= 37.
%K nonn,hard,more
%O 0,3
%A _Joerg Arndt_, Jan 19 2015
%E a(7)-a(9) from Cyvin, Brunvoll & Cyvin 1992 (Table 31) added by _Andrey Zabolotskiy_, Feb 16 2023