OFFSET
0,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 880, 0, 0, 0, -1).
FORMULA
G.f.: -(x^2-x-1)*(x^4+21*x^2+1) / (x^8-880*x^4+1). - Colin Barker, Nov 25 2013
a(n) = 880*a(n-4) - a(n-8) for n>7. - Vincenzo Librandi, Dec 25 2013
MATHEMATICA
Denominator[Convergents[Sqrt[439], 30]] (* Vincenzo Librandi, Dec 25 2013 *)
PROG
(Magma) I:=[1, 1, 20, 21, 860, 881, 17599, 18480]; [n le 8 select I[n] else 880*Self(n-4)-Self(n-8): n in [1..40]]; // Vincenzo Librandi, Dec 25 2013
CROSSREFS
KEYWORD
nonn,frac,easy,less
AUTHOR
EXTENSIONS
More terms from Colin Barker, Nov 25 2013
STATUS
approved