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A107943 a(n) = (n+1)*(n+2)^2*(n+3)^2*(n+4)^2*(n+5)*(2n+3)/8640. 0
1, 25, 245, 1470, 6468, 22932, 69300, 185130, 448305, 1002001, 2095093, 4140500, 7796880, 14080080, 24511824, 41314284, 67660425, 107991345, 168413245, 257188162, 385334180, 567352500, 822100500, 1173831750, 1653425865 (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

Table of n, a(n) for n=0..24.

FORMULA

G.f.: (1+15*x+40*x^2+25*x^3+3*x^4)/(1-x)^10. - Bruno Berselli, Apr 19 2011

MAPLE

a:=n->(1/8640)*(n+1)*(n+2)^2*(n+3)^2*(n+4)^2*(n+5)*(2*n+3): seq(a(n), n=0..30);

MATHEMATICA

Table[((n+1)(n+2)^2(n+3)^2(n+4)^2(n+5)(2n+3))/8640, {n, 0, 30}]  (* Harvey P. Dale, Apr 19 2011 *)

CROSSREFS

Sequence in context: A088890 A108178 A278849 * A125388 A126546 A023073

Adjacent sequences:  A107940 A107941 A107942 * A107944 A107945 A107946

KEYWORD

nonn

AUTHOR

Emeric Deutsch, Jun 12 2005

STATUS

approved

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Last modified December 11 00:29 EST 2016. Contains 279033 sequences.