OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0,82,0,-1).
FORMULA
G.f.: (1 + 4*x - x^2)/(1 - 82*x^2 + x^4). - Vincenzo Librandi, Dec 12 2013
a(n) = 82*a(n-2) - a(n-4). - Vincenzo Librandi, Dec 12 2013
MATHEMATICA
Denominator/@Convergents[Sqrt[105], 30] (* Harvey P. Dale, Apr 02 2011 *)
CoefficientList[Series[(1 + 4 x - x^2)/(1 - 82 x^2 + x^4), {x, 0, 30}], x] (* Vincenzo Librandi, Dec 12 2013*)
PROG
(Magma) I:=[1, 4, 81, 328]; [n le 4 select I[n] else 82*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Dec 12 2013
CROSSREFS
KEYWORD
nonn,frac,easy
AUTHOR
EXTENSIONS
a(19) from Vincenzo Librandi, Dec 12 2013
STATUS
approved