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.: -(x^2-2*x-1) / (x^4-82*x^2+1). - Colin Barker, Nov 25 2013
a(n) = 82*a(n-2) - a(n-4) for n>3. - Vincenzo Librandi, Dec 24 2013
MATHEMATICA
Denominator[Convergents[Sqrt[420], 30]] (* Vincenzo Librandi, Dec 24 2013 *)
PROG
(Magma) I:=[1, 2, 81, 164]; [n le 4 select I[n] else 82*Self(n-2)-Self(n-4): n in [1..40]]; // Vincenzo Librandi, Dec 24 2013
CROSSREFS
KEYWORD
nonn,frac,easy
AUTHOR
EXTENSIONS
More terms from Colin Barker, Nov 25 2013
STATUS
approved