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%I #8 Aug 09 2015 12:00:54
%S 4,16,60,208,680,2136,6524,19520,57492,167240,481624,1375536
%N Number of conjugated cycles composed of six carbons in (n,n)-nanotubes in terms of the number of naphthalene units.
%C See Table 2 on page 412 of Lukovits and Janezic paper for details.
%H I. Lukovits et al. <a href="http://dx.doi.org/10.1021/ci034240k">Enumeration of conjugated circuits in nanotubes</a>, J. Chem. Inf. Comput. Sci. 44 (2004), 410-414.
%H <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (6, -11, 6, -1).
%F Conjecture: a(n)=6a(n-1)-11a(n-2)+6a(n-3)-a(n-4)=4*A117202(n). G.f.: 4*x*(1-2*x+2*x^2)/(x^2-3*x+1)^2. [From _R. J. Mathar_, Mar 18 2009]
%e If n=5 then the number of conjugated cycles composed of six carbons in (n,n)-nanotubes is 680 which is the fifth term in the sequence. Here n is the number of naphthalene units.
%K nonn
%O 1,1
%A _Parthasarathy Nambi_, Aug 22 2006
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