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A107941 a(n) = (n+1)(n+2)^2*(n+3)^2*(n+4)^2*(n+5)(3n^2 + 13n + 15)/43200. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,2
COMMENTS
Kekulé numbers for certain benzenoids.
REFERENCES
S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 229).
LINKS
Index entries for linear recurrences with constant coefficients, signature (11,-55,165,-330,462,-462,330,-165,55,-11,1).
FORMULA
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
MAPLE
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);
CROSSREFS
Sequence in context: A138440 A307008 A161347 * A142684 A042868 A258944
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Jun 12 2005
STATUS
approved

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Last modified June 20 08:07 EDT 2024. Contains 373512 sequences. (Running on oeis4.)