OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 586, 0, 0, 0, -1).
FORMULA
G.f.: -(x^7-20*x^6+21*x^5-272*x^4-293*x^3-272*x^2-21*x-20)/(x^8-586*x^4+1). - Vincenzo Librandi, Nov 10 2013
a(n) = 586*a(n-4)-a(n-8). - Vincenzo Librandi, Nov 10 2013
MATHEMATICA
Numerator[Convergents[Sqrt[438], 30]] (* or *) CoefficientList[Series[-(x^7 - 20 x^6 + 21 x^5 - 272 x^4 - 293 x^3 - 272 x^2 - 21 x - 20)/(x^8 - 586 x^4 + 1), {x, 0, 25}], x] (* Vincenzo Librandi, Nov 10 2013 *)
PROG
(Magma) I:=[20, 21, 272, 293, 11992, 12285, 159412, 171697]; [n le 8 select I[n] else 586*Self(n-4)-Self(n-8): n in [1..25]]; // Vincenzo Librandi, Nov 10 2013
CROSSREFS
KEYWORD
nonn,cofr,frac,easy,less
AUTHOR
STATUS
approved