OFFSET
0,3
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0,0,0,248,0,0,0,-1).
FORMULA
G.f.: -(x^2 - x - 1)*(x^4 + 5*x^2 + 1) / (x^8 - 248*x^4 + 1). - Colin Barker, Dec 03 2013
a(n) = 248*a(n-4) - a(n-8) for n > 7. - Vincenzo Librandi, Jan 16 2014
MATHEMATICA
Denominator[Convergents[Sqrt[615], 30]] (* Vincenzo Librandi, Jan 16 2014 *)
PROG
(Magma) I:=[1, 1, 4, 5, 244, 249, 991, 1240]; [n le 8 select I[n] else 248*Self(n-4)-Self(n-8): n in [1..30]]; // Vincenzo Librandi, Jan 16 2014
CROSSREFS
KEYWORD
nonn,frac,easy
AUTHOR
EXTENSIONS
More terms from Colin Barker, Dec 03 2013
STATUS
approved