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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

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

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

Adjacent sequences:  A107938 A107939 A107940 * A107942 A107943 A107944

KEYWORD

nonn,easy

AUTHOR

Emeric Deutsch, Jun 12 2005

STATUS

approved

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Last modified December 1 22:24 EST 2020. Contains 338858 sequences. (Running on oeis4.)