This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A041189 #25 Aug 11 2024 09:55:17
%S A041189 1,4,81,328,6641,26892,544481,2204816,44640801,180768020,3660001201,
%T A041189 14820772824,300075457681,1215122603548,24602527528641,99625232718112,
%U A041189 2017107181890881,8168053960281636,165378186387523601,669680799510376040
%N A041189 Denominators of continued fraction convergents to sqrt(105).
%H A041189 Vincenzo Librandi, <a href="/A041189/b041189.txt">Table of n, a(n) for n = 0..200</a>
%H A041189 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,82,0,-1).
%F A041189 G.f.: (1 + 4*x - x^2)/(1 - 82*x^2 + x^4). - _Vincenzo Librandi_, Dec 12 2013
%F A041189 a(n) = 82*a(n-2) - a(n-4). - _Vincenzo Librandi_, Dec 12 2013
%t A041189 Denominator/@Convergents[Sqrt[105],30] (* _Harvey P. Dale_, Apr 02 2011 *)
%t A041189 CoefficientList[Series[(1 + 4 x - x^2)/(1 - 82 x^2 + x^4), {x, 0, 30}], x] (* _Vincenzo Librandi_, Dec 12 2013*)
%o A041189 (Magma) I:=[1,4,81,328]; [n le 4 select I[n] else 82*Self(n-2)-Self(n-4): n in [1..30]]; // _Vincenzo Librandi_, Dec 12 2013
%Y A041189 Cf. A040094, A041188 (numerators), A176461.
%K A041189 nonn,frac,easy
%O A041189 0,2
%A A041189 _N. J. A. Sloane_
%E A041189 a(19) from _Vincenzo Librandi_, Dec 12 2013