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%I #12 Sep 08 2022 08:45:19
%S 1,19,142,665,2338,6762,16968,38214,79035,152581,278278,483847,807716,
%T 1301860,2035104,3096924,4601781,6694023,9553390,13401157,18506950,
%U 25196270,33858760,44957250,59037615,76739481,98807814,126105427
%N a(n) = (n+1)(n+2)^2*(n+3)(n+4)(5n^2 + 18n + 15)/720.
%C Kekulé numbers for certain benzenoids.
%D S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 229).
%H Vincenzo Librandi, <a href="/A107962/b107962.txt">Table of n, a(n) for n = 0..1000</a>
%F O.g.f.: (1+11*x+18*x^2+5*x^3)/(-1+x)^8. - _R. J. Mathar_, Apr 07 2008
%p a:=n->(1/720)*(n+1)*(n+2)^2*(n+3)*(n+4)*(5*n^2+18*n+15): seq(a(n),n=0..30);
%o (Magma) [Floor((1/720)*(n+1)*(n+2)^2*(n+3)*(n+4)*(5*n^2+18*n+15)): n in [0..30]]; // _Vincenzo Librandi_, Mar 28 2012
%K nonn,easy
%O 0,2
%A _Emeric Deutsch_, Jun 12 2005
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