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. 230).
LINKS
Index entries for linear recurrences with constant coefficients, signature (7, -21, 35, -35, 21, -7, 1).
FORMULA
From R. J. Mathar, Apr 07 2008: (Start)
O.g.f.: -(1 + 11x + 18x^2 + 5x^3)/(-1+x)^7.
MAPLE
a:=n->(1/720)*(n+1)*(n+2)*(n+3)*(35*n^3+153*n^2+232*n+120): seq(a(n), n=0..35);
MATHEMATICA
Table[(n+1)(n+2)(n+3)(35n^3+153n^2+232n+120)/720, {n, 0, 30}] (* or *) LinearRecurrence[{7, -21, 35, -35, 21, -7, 1}, {1, 18, 123, 523, 1673, 4424, 10206}, 30] (* Harvey P. Dale, Jan 05 2022 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Jun 12 2005
STATUS
approved