OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0,102,0,-1).
FORMULA
G.f.: (1 + x)*(25 + 26*x - x^2)/((1 - 10*x - x^2)*(1 + 10*x - x^2)) = (25 + 51*x + 25*x^2 - x^3)/(1 - 102*x^2 + x^4). - Vincenzo Librandi, Nov 20 2013
a(n) = 102*a(n-2) - a(n-4). - Vincenzo Librandi, Nov 20 2013
MATHEMATICA
Numerator[Convergents[Sqrt[650], 30]] (* or *) CoefficientList[Series[(25 + 51 x + 25 x^2 - x^3)/(1 - 102 x^2 + x^4), {x, 0, 30}], x] (* Vincenzo Librandi, Nov 20 2013 *)
PROG
(Magma) I:=[25, 51, 2575, 5201]; [n le 4 select I[n] else 102*Self(n-2)-Self(n-4): n in [1..30]]; // Vincenzo Librandi, Nov 20 2013
CROSSREFS
KEYWORD
nonn,cofr,frac,easy
AUTHOR
STATUS
approved