OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0,252,0,-1).
FORMULA
G.f.: (25 +126*x +25*x^2 -x^3)/(x^4 -252*x^2 +1). - Vincenzo Librandi, Nov 19 2013
a(n) = 252*a(n-2) - a(n-4). - Vincenzo Librandi, Nov 19 2013
MATHEMATICA
Numerator[Convergents[Sqrt[635], 30]] (* Harvey P. Dale, Dec 15 2012 *)
CoefficientList[Series[(25 + 126 x + 25 x^2 - x^3)/(x^4 - 252 x^2 + 1), {x, 0, 30}], x](* Vincenzo Librandi, Nov 19 2013 *)
PROG
(Magma) I:=[25, 126, 6325, 31751]; [n le 4 select I[n] else 252*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Nov 19 2013
CROSSREFS
KEYWORD
nonn,cofr,frac,easy
AUTHOR
STATUS
approved