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, # 29).
LINKS
Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1).
FORMULA
From Colin Barker, Apr 23 2020: (Start)
G.f.: (1 + 16*x + 44*x^2 + 27*x^3 + 3*x^4) / (1 - x)^8.
a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>7.
(End)
MAPLE
a:=n->(n+1)*(n+2)^3*(n+3)*(13*n^2+37*n+30)/720: seq(a(n), n=0..32);
PROG
(PARI) Vec((1 + 16*x + 44*x^2 + 27*x^3 + 3*x^4) / (1 - x)^8 + O(x^30)) \\ Colin Barker, Apr 23 2020
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Jun 17 2005
STATUS
approved