OFFSET
0,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
Index entries for linear recurrences with constant coefficients, signature (0,322,0,-1).
FORMULA
G.f.: -(x^3-20*x^2-161*x-20) / ((x^2-18*x+1)*(x^2+18*x+1)). - Vincenzo Librandi, Nov 08 2013, simplified by Colin Barker, Dec 28 2013
a(n) = 322*a(n-2)-a(n-4). - Vincenzo Librandi, Nov 08 2013, simplified by Colin Barker, Dec 28 2013
MATHEMATICA
Numerator[Convergents[Sqrt[405], 30]] (* Vincenzo Librandi, Nov 07 2013 *)
CoefficientList[Series[(20 + 161 x + 6460 x^2 + 51841 x^3 + 6460 x^4 - 161 x^5 + 20 x^6 - x^7)/(1 - 103682 x^4 + x^8), {x, 0, 30}], x] (* Vincenzo Librandi, Nov 08 2013 *)
LinearRecurrence[{0, 322, 0, -1}, {20, 161, 6460, 51841}, 20] (* Harvey P. Dale, Apr 28 2022 *)
PROG
(Magma) I:=[20, 161, 6460, 51841, 2080100, 16692641, 669785740, 5374978561]; [n le 8 select I[n] else 103682*Self(n-4)-Self(n-8): n in [1..30]]; // Vincenzo Librandi, Nov 08 2013
CROSSREFS
KEYWORD
nonn,frac,easy,less
AUTHOR
EXTENSIONS
More terms from Colin Barker, Dec 28 2013
STATUS
approved