%I A109113
%S A109113 2,14,90,582,3762,24318,157194,1016118,6568290,42458094,274453434,
%T A109113 1774094886,11467929618,74129862366,479182963050,3097487365398,
%U A109113 20022473081538,129427300585422,836631222757146,5408069238299142
%N A109113 a(n)=6a(n-1)+3a(n-2), a(0)=2, a(1)=14.
%C A109113 Kekule numbers for certain benzenoids.
%D A109113 S. J. Cyvin and I. Gutman, Kekule structures in benzenoid hydrocarbons, 
               Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (pp. 
               302, P_{15}).
%F A109113 a(n)=[(3+2sqrt(3))^(n+1)+(3-2sqrt(3))^(n+1)]/3. G=2(1+z)/(1-6z-3z^2).
%p A109113 a[0]:=2: a[1]:=14: for n from 2 to 25 do a[n]:=6*a[n-1]+3*a[n-2] od: 
               seq(a[n],n=0..22);
%Y A109113 Sequence in context: A162478 A065892 A139183 this_sequence A081959 A002464 
               A020063
%Y A109113 Adjacent sequences: A109110 A109111 A109112 this_sequence A109114 A109115 
               A109116
%K A109113 nonn
%O A109113 0,1
%A A109113 Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 19 2005