%I A109111
%S A109111 2,510,126000,31117500,7684875000,1897880625000,468706500000000,
%T A109111 115753214531250000,28586773757812500000,7059878528554687500000,
%U A109111 1743529551820312500000000,430587479058662109375000000
%N A109111 (1/sqrt(595))((sqrt(595)+26)(125+5sqrt(595))^n+(sqrt(595)-26)(125-5sqrt(595))^n).
%C A109111 Kekule numbers for certain benzenoids.
%D A109111 S. J. Cyvin and I. Gutman, Kekule structures in benzenoid hydrocarbons, 
               Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p.292).
%F A109111 G.f.=2(1+5z)/(1-250z+750z^2).
%p A109111 a:=n->(1/sqrt(595))*((sqrt(595)+26)*(125+5*sqrt(595))^n+(sqrt(595)-26)*(125-5*sqrt(595))^n): 
               seq(expand(a(n)),n=0..13);
%Y A109111 Sequence in context: A027655 A024032 A109032 this_sequence A004886 A139302 
               A003391
%Y A109111 Adjacent sequences: A109108 A109109 A109110 this_sequence A109112 A109113 
               A109114
%K A109111 nonn
%O A109111 0,1
%A A109111 Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 19 2005