OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0,50,0,-1).
FORMULA
G.f.: -(x^2-4*x-1) / (x^4-50*x^2+1). - Colin Barker, Nov 12 2013
a(n) = 50*a(n-2) - a(n-4). - Vincenzo Librandi, Dec 10 2013
MATHEMATICA
Table[Denominator[FromContinuedFraction[ContinuedFraction[Sqrt[39], n]]], {n, 1, 50}] (* Vladimir Joseph Stephan Orlovsky, Mar 21 2011 *)
Denominator[Convergents[Sqrt[39], 30]] (* Vincenzo Librandi, Dec 10 2013 *)
PROG
(Magma) I:=[1, 4, 49, 200]; [n le 4 select I[n] else 50*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Dec 10 2013
CROSSREFS
KEYWORD
nonn,cofr,frac,easy
AUTHOR
EXTENSIONS
More terms from Colin Barker, Nov 12 2013
STATUS
approved