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 A107916 a(n) = binomial(n+3,2)*binomial(n+4,3)*binomial(n+5,5)/12. 1
 1, 30, 350, 2450, 12348, 49392, 166320, 490050, 1297725, 3149146, 7105098, 15071420, 30321200, 58262400, 107535744, 191548044, 330569505, 554550150, 906840550, 1449035742, 2267198780, 3479762000, 5247450000, 7785618750, 11379460365, 16402583106, 23339541330 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS KekulĂ© numbers for certain benzenoids. REFERENCES S. J. Cyvin and I. Gutman, KekulĂ© structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 229). LINKS T. D. Noe, Table of n, a(n) for n = 0..1000 Index entries for linear recurrences with constant coefficients, signature (11,-55,165,-330,462,-462,330,-165,55,-11,1). FORMULA a(n) = (1/17280)(n+1)(n+2)^3*(n+3)^3*(n+4)^2*(n+5). G.f.: -(2*x^5+28*x^4+85*x^3+75*x^2+19*x+1)/(x-1)^11. - Colin Barker, Sep 20 2012 MAPLE a:=n->(1/12)*binomial(n+3, 2)*binomial(n+4, 3)*binomial(n+5, 5): seq(a(n), n=0..30); CROSSREFS Sequence in context: A115500 A214085 A125418 * A091775 A222086 A008656 Adjacent sequences:  A107913 A107914 A107915 * A107917 A107918 A107919 KEYWORD nonn,easy AUTHOR Emeric Deutsch, Jun 12 2005 STATUS approved

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Last modified September 19 15:43 EDT 2020. Contains 337178 sequences. (Running on oeis4.)