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A107941
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a(n) = (n+1)(n+2)^2*(n+3)^2*(n+4)^2*(n+5)(3n^2 + 13n + 15)/43200.
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1
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1, 31, 371, 2646, 13524, 54684, 185724, 551034, 1467609, 3578575, 8107099, 17257604, 34826064, 67098864, 124140528, 221594796, 383151321, 643861911, 1054526011, 1687405258, 2643571700, 4062243900, 6132519900, 9107976150, 13324667265, 19223133111, 27375097491
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OFFSET
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0,2
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COMMENTS
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Kekulé numbers for certain benzenoids.
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REFERENCES
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S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 229).
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (11,-55,165,-330,462,-462,330,-165,55,-11,1).
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FORMULA
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G.f.: (1+20*x+85*x^2+105*x^3+38*x^4+3*x^5)/(1-x)^11. - Colin Barker, Sep 18 2012
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MAPLE
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a:=n->(1/43200)*(n+1)*(n+2)^2*(n+3)^2*(n+4)^2*(n+5)*(3*n^2+13*n+15): seq(a(n), n=0..28);
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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