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. 233, # 7).
LINKS
Index entries for linear recurrences with constant coefficients, signature (8,-28,56,-70,56,-28,8,-1).
FORMULA
G.f.: (1 + 9z + 14z^2 + 4z^3)/(1-z)^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). - Wesley Ivan Hurt, May 23 2015
MAPLE
A108682:=n->(n+1)*(n+2)^2*(n+3)*(n+4)*(4*n^2+15*n+15)/720: seq(A108682(n), n=0..50); # Wesley Ivan Hurt, May 23 2015
MATHEMATICA
Table[(n+1)(n+2)^2(n+3)(n+4)(4n^2+15n+15)/720, {n, 0, 40}] (* or *)
CoefficientList[Series[(1+9x+14x^2+4x^3)/(1-x)^8, {x, 0, 40}], x] (* Harvey P. Dale, Mar 28 2011 *)
PROG
(Magma) [(n+1)*(n+2)^2*(n+3)*(n+4)*(4*n^2+15*n+15)/720 : n in [0..50]]; // Wesley Ivan Hurt, May 23 2015
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Emeric Deutsch, Jun 18 2005
STATUS
approved