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 A041833 #23 Jul 09 2025 01:45:03
%S A041833 1,1,10,21,199,220,8999,9219,91970,193159,1830401,2023560,82772801,
%T A041833 84796361,845940050,1776676461,16836028199,18612704660,761344214599,
%U A041833 779956919259,7780956487930,16341869895119,154857785544001,171199655439120,7002844003108801
%N A041833 Denominators of continued fraction convergents to sqrt(437).
%H A041833 Vincenzo Librandi, <a href="/A041833/b041833.txt">Table of n, a(n) for n = 0..200</a>
%H A041833 <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 0, 0, 0, 9198, 0, 0, 0, 0, 0, -1).
%F A041833 G.f.: -(x^10 -x^9 +10*x^8 -21*x^7 +199*x^6 -220*x^5 -199*x^4 -21*x^3 -10*x^2 -x -1) / ((x^4 -21*x^2 +1)*(x^8 +21*x^6 +440*x^4 +21*x^2 +1)). - _Colin Barker_, Nov 25 2013
%F A041833 a(n) = 9198*a(n-6) - a(n-12) for n>11. - _Vincenzo Librandi_, Dec 25 2013
%t A041833 Table[Denominator[FromContinuedFraction[ContinuedFraction[Sqrt[437], n]]], {n, 1, 50}] (* _Vladimir Joseph Stephan Orlovsky_, Jun 23 2011 *)
%t A041833 Denominator[Convergents[Sqrt[437], 30]] (* _Vincenzo Librandi_, Dec 25 2013 *)
%o A041833 (Magma) I:=[1,1,10,21,199,220,8999,9219,91970,193159, 1830401,2023560]; [n le 12 select I[n] else 9198*Self(n-6)-Self(n-12): n in [1..40]]; // _Vincenzo Librandi_, Dec 25 2013
%Y A041833 Cf. A041832, A040416.
%K A041833 nonn,easy,frac
%O A041833 0,3
%A A041833 _N. J. A. Sloane_