OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0,0,0,250,0,0,0,-1).
FORMULA
G.f.: (20 + 21*x + 104*x^2 + 125*x^3 + 104*x^4 - 21*x^5 + 20*x^6 - x^7)/(1 - 250*x^4 + x^8). - Vincenzo Librandi, Nov 09 2013
a(n) = 250*a(n-4) - a(n-8). - Vincenzo Librandi, Nov 09 2013
MATHEMATICA
Numerator[Convergents[Sqrt[434], 30]] (* or *) CoefficientList[Series[(20 + 21 x + 104 x^2 + 125 x^3 + 104 x^4 - 21 x^5 + 20 x^6 - x^7)/(1 - 250 x^4 + x^8), {x, 0, 30}], x] (* Vincenzo Librandi, Nov 09 2013 *)
PROG
(Magma) I:=[20, 21, 104, 125, 5104, 5229, 26020, 31249]; [n le 8 select I[n] else 250*Self(n-4)-Self(n-8): n in [1..40]]; // Vincenzo Librandi, Nov 09 2013
CROSSREFS
KEYWORD
nonn,cofr,frac,easy,less
AUTHOR
STATUS
approved