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A114244 a(n) = (n+1)(n+2)^2*(n+3)(7n^2 + 28n + 30)/360. 2
1, 13, 76, 295, 889, 2254, 5040, 10242, 19305, 34243, 57772, 93457, 145873, 220780, 325312, 468180, 659889, 912969, 1242220, 1664971, 2201353, 2874586, 3711280, 4741750, 6000345, 7525791, 9361548, 11556181, 14163745, 17244184, 20863744 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Kekulé numbers for certain benzenoids.

First differences of A114242. - Peter Bala, Sep 21 2007

REFERENCES

S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (pp. 167-169, Table 10.5/II/5).

LINKS

Table of n, a(n) for n=0..30.

FORMULA

G.f.: (1+x)(1 + 5x + x^2)/(1-x)^7.

MAPLE

a:=n->(n+1)*(n+2)^2*(n+3)*(7*n^2+28*n+30)/360: seq(a(n), n=0..35);

CROSSREFS

Cf. A114242.

Sequence in context: A051361 A114070 A005340 * A050485 A034265 A282643

Adjacent sequences:  A114241 A114242 A114243 * A114245 A114246 A114247

KEYWORD

nonn,easy

AUTHOR

Emeric Deutsch, Nov 18 2005

STATUS

approved

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Last modified August 17 18:38 EDT 2017. Contains 290655 sequences.