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A108650 a(n) = (n+1)^2*(n+2)*(n+3)*(3*n+4)/24. 2
1, 14, 75, 260, 700, 1596, 3234, 6000, 10395, 17050, 26741, 40404, 59150, 84280, 117300, 159936, 214149, 282150, 366415, 469700, 595056, 745844, 925750, 1138800, 1389375, 1682226, 2022489, 2415700, 2867810, 3385200, 3974696, 4643584 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Kekulé numbers for certain benzenoids.

a(n) = A001477*A001296 or n*A001296. - Zerinvary Lajos, Jan 20 2007

REFERENCES

S. J. Cyvin and I. Gutman, Kekulé structures in benzenoid hydrocarbons, Lecture Notes in Chemistry, No. 46, Springer, New York, 1988 (p. 230, no. 26).

LINKS

Bo Gyu Jeong, Table of n, a(n) for n = 0..5000

C. Krishnamachari, The operator (xD)^n, J. Indian Math. Soc., 15 (1923),3-4. [Annotated scanned copy]

FORMULA

a(n) = (n+1)*stirling2(n+3,n+1). - Zerinvary Lajos, Jan 20 2007

MAPLE

a:= n-> (n+1)^2*(n+2)*(n+3)*(3*n+4)/24: seq(a(n), n=0..36);

seq((n+1)*stirling2(n+3, n+1), n=0..32); # Zerinvary Lajos, Jan 20 2007

MATHEMATICA

Table[((n+1)^2 (n+2)(n+3)(3n+4))/24, {n, 0, 40}] (* or *) Table[n StirlingS2[n+2, n], {n, 40}] (* Harvey P. Dale, Dec 01 2013 *)

CROSSREFS

Sequence in context: A205583 A167633 A196411 * A093567 A296996 A270704

Adjacent sequences:  A108647 A108648 A108649 * A108651 A108652 A108653

KEYWORD

nonn

AUTHOR

Emeric Deutsch, Jun 13 2005

STATUS

approved

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Last modified October 22 03:49 EDT 2018. Contains 316431 sequences. (Running on oeis4.)