OFFSET
0,2
COMMENTS
Essentially CONV transform of A079496.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Yujun Yang and Heping Zhang, Kirchhoff Index of linear hexagonal chains, Int. J. Quant. Chem. 108 (2008) 503-512.
Index entries for linear recurrences with constant coefficients, signature (0,12,0,-38,0,12,0,-1).
FORMULA
O.g.f.: ((1+3*x-x^2-x^3)/(1-6*x^2+x^4))^2.
a(n) = 12*a(n-2)-38*a(n-4)+12*a(n-6)-a(n-8).
MATHEMATICA
CoefficientList[Series[((1 + 3 x - x^2 - x^3)/(1 - 6 x^2 + x^4))^2, {x, 0, 40}], x] (* Vincenzo Librandi, Dec 12 2012 *)
PROG
(Magma) I:=[1, 6, 19, 64, 185, 542, 1511, 4144]; [n le 8 select I[n] else 12*Self(n-2)-38*Self(n-4)+12*Self(n-6)-Self(n-8): n in [1..40]]; // Vincenzo Librandi, Dec 12 2012
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
R. J. Mathar, Apr 04 2008
STATUS
approved