A109121 a(n) = 10(n+1)^3*(2n+1)(7n+5)^2.

250, 34560, 487350, 3028480, 12251250, 38016000, 98499310, 223948800, 461143530, 878560000, 1572243750, 2672386560, 4350609250, 6827950080, 10383558750, 15364096000, 22193838810, 31385491200, 43551700630

Offset

0,1

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. 311).

Links

Table of n, a(n) for n=0..18.

Index entries for linear recurrences with constant coefficients, signature (7,-21,35,-35,21,-7,1).

Formula

G.f.: 10(25 + 3281z + 25068z^2 + 33404z^3 + 8539z^4 + 243z^5)/(1-z)^7.

Maple

a:=n->10*(n+1)^3*(2*n+1)*(7*n+5)^2: seq(a(n), n=0..28);

Mathematica

Table[10(n+1)^3(2n+1)(7n+5)^2, {n, 0, 30}] (* Harvey P. Dale, Aug 07 2019 *)

Crossrefs

Sequence in context: A249199 A249214 A249321 * A253005 A267972 A267995

Adjacent sequences: A109118 A109119 A109120 * A109122 A109123 A109124

Keyword

nonn,easy

Author

Emeric Deutsch, Jun 19 2005

Status

approved