OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0,56,0,-1).
FORMULA
G.f.: (27 + 28*x + 27*x^2 - x^3)/(1 - 56*x^2 + x^4). - Vincenzo Librandi, Nov 26 2013
a(n) = 56*a(n-2) - a(n-4). - Vincenzo Librandi, Nov 26 2013
MATHEMATICA
Numerator[Convergents[Sqrt[783], 30]] (* or *) CoefficientList[Series[(27 + 28 x + 27 x^2 - x^3)/(1 - 56 x^2 + x^4), {x, 0, 30}], x] (* Vincenzo Librandi, Nov 25 2013 *)
LinearRecurrence[{0, 56, 0, -1}, {27, 28, 1539, 1567}, 30] (* Harvey P. Dale, Apr 28 2016 *)
PROG
(Magma) I:=[27, 28, 1539, 1567]; [n le 4 select I[n] else 56*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Nov 26 2013
CROSSREFS
KEYWORD
nonn,cofr,frac,easy
AUTHOR
STATUS
approved