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A108676 a(n) = (n+1)^2*(n+2)*(5*n^2 + 15*n + 12)/24. 0
1, 16, 93, 340, 950, 2226, 4606, 8688, 15255, 25300, 40051, 60996, 89908, 128870, 180300, 246976, 332061, 439128, 572185, 735700, 934626, 1174426, 1461098, 1801200, 2201875, 2670876, 3216591, 3848068, 4575040, 5407950, 6357976 (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. 231, # 37).

LINKS

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

FORMULA

G.f.: (1 + 10*x + 12*x^2 + 2*x^3)/(1-x)^6.

MAPLE

a:=n->(n+1)^2*(n+2)*(5*n^2+15*n+12)/24: seq(a(n), n=0..36);

MATHEMATICA

Table[(n+1)^2(n+2)(5n^2+15n+12)/24, {n, 0, 30}] (* Harvey P. Dale, Apr 10 2022 *)

CROSSREFS

Sequence in context: A027938 A301527 A185458 * A304344 A316215 A305639

Adjacent sequences: A108673 A108674 A108675 * A108677 A108678 A108679

KEYWORD

nonn,easy

AUTHOR

Emeric Deutsch, Jun 17 2005

STATUS

approved

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Last modified December 3 11:20 EST 2022. Contains 358517 sequences. (Running on oeis4.)