OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0,0,0,610,0,0,0,-1).
FORMULA
G.f.: -(x^2 - 2*x - 1)*(x^4 + 6*x^2 + 1) / (x^8 - 610*x^4 + 1). - Colin Barker, Dec 05 2013
a(n) = 610*a(n-4) - a(n-8) for n > 7. - Vincenzo Librandi, Jan 18 2014
MATHEMATICA
Denominator[Convergents[Sqrt[646], 30]] (* Vincenzo Librandi, Jan 18 2014 *)
PROG
(Magma) I:=[1, 2, 5, 12, 605, 1222, 3049, 7320]; [n le 8 select I[n] else 610*Self(n-4)-Self(n-8): n in [1..30]]; // Vincenzo Librandi, Jan 18 2014
CROSSREFS
KEYWORD
nonn,frac,easy
AUTHOR
EXTENSIONS
More terms from Colin Barker, Dec 05 2013
STATUS
approved