%I #17 Sep 08 2022 08:44:55
%S 1,3,127,384,16255,49149,2080513,6290688,266289409,805158915,
%T 34082963839,103054050432,4362353081983,13190113296381,
%U 558347111529985,1688231447886336,71464067922756097,216080435216154627,9146842347001250431,27656607476219905920
%N Denominators of continued fraction convergents to sqrt(455).
%H Vincenzo Librandi, <a href="/A041867/b041867.txt">Table of n, a(n) for n = 0..200</a>
%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (0,128,0,-1).
%F G.f.: -(x^2-3*x-1) / (x^4-128*x^2+1). - _Colin Barker_, Nov 26 2013
%F a(n) = 128*a(n-2) - a(n-4) for n>3. - _Vincenzo Librandi_, Dec 26 2013
%t Denominator[Convergents[Sqrt[455], 30]] (* _Harvey P. Dale_, Aug 23 2013 *)
%t CoefficientList[Series[(1 + 3 x - x^2)/(x^4 - 128 x^2 + 1), {x, 0, 30}], x] (* _Vincenzo Librandi_, Dec 26 2013 *)
%o (Magma) I:=[1,3,127,384]; [n le 4 select I[n] else 128*Self(n-2)-Self(n-4): n in [1..40]]; // _Vincenzo Librandi_, Dec 26 2013
%Y Cf. A041866, A040433.
%K nonn,frac,easy
%O 0,2
%A _N. J. A. Sloane_.
%E More terms from _Colin Barker_, Nov 26 2013
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