OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0,86,0,-1).
FORMULA
G.f.: (21 +43*x +21*x^2 -x^3)/(1 -86*x^2 +x^4). - Vincenzo Librandi, Nov 11 2013
a(n) = 86*a(n-2) -a(n-4). - Vincenzo Librandi, Nov 11 2013
MATHEMATICA
Numerator[Convergents[Sqrt[462], 30]] (* or *) CoefficientList[Series[(21 + 43 x + 21 x^2 - x^3)/(1 - 86 x^2 + x^4), {x, 0, 25}], x] (* Vincenzo Librandi, Nov 11 2013 *)
LinearRecurrence[{0, 86, 0, -1}, {21, 43, 1827, 3697}, 30] (* Harvey P. Dale, Jul 25 2015 *)
PROG
(Magma) I:=[21, 43, 1827, 3697]; [n le 4 select I[n] else 86*Self(n-2)-Self(n-4): n in [1..20]]; // Vincenzo Librandi, Nov 11 2013
CROSSREFS
KEYWORD
nonn,cofr,frac,easy,less
AUTHOR
STATUS
approved