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A109122 4(n+1)^2*(3n+1)^2*(12n^2+20n+5). 0
20, 9472, 164052, 1107200, 4681300, 14929920, 39411092, 90821632, 188932500, 362835200, 653499220, 1116640512, 1825901012, 2876339200, 4388231700, 6511185920, 9428563732, 13362216192, 18577529300, 25388780800, 34164808020 (list; graph; refs; listen; history; internal format)
OFFSET

0,1

COMMENTS

Kekule numbers for certain benzenoids.

REFERENCES

S. J. Cyvin and I. Gutman, Kekule structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (pp. 311).

FORMULA

G.f.=4(5+2333z+24542z^2+39262z^3+11293z^4+325z^5)/(1-z)^7.

MAPLE

a:=n->4*(n+1)^2*(3*n+1)^2*(12*n^2+20*n+5): seq(a(n), n=0..24);

CROSSREFS

Sequence in context: A135292 A013725 A203308 * A135420 A045811 A086687

Adjacent sequences:  A109119 A109120 A109121 * A109123 A109124 A109125

KEYWORD

nonn

AUTHOR

Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 19 2005

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Last modified February 16 17:48 EST 2012. Contains 205939 sequences.