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 A041155 #22 Jul 09 2025 00:21:08
%S A041155 1,3,55,168,3079,9405,172369,526512,9649585,29475267,540204391,
%T A041155 1650088440,30241796311,92375477373,1693000389025,5171376644448,
%U A041155 94777779989089,289504716611715,5305862678999959,16207092753611592,297033532244008615,907307689485637437
%N A041155 Denominators of continued fraction convergents to sqrt(87).
%H A041155 Vincenzo Librandi, <a href="/A041155/b041155.txt">Table of n, a(n) for n = 0..200</a>
%H A041155 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (0,56,0,-1).
%F A041155 G.f.: (1 +3*x -x^2)/(x^4 -56*x^2 +1), - _Vincenzo Librandi_, Dec 12 2013
%F A041155 a(n) = 56*a(n-2) - a(n-4). - _Vincenzo Librandi_, Dec 12 2013
%t A041155 Denominator/@Convergents[Sqrt[87], 50] (* _Vladimir Joseph Stephan Orlovsky_, Jul 05 2011 *)
%t A041155 CoefficientList[Series[(1 + 3 x - x^2)/(x^4 - 56 x^2 + 1), {x, 0, 30}], x] (* _Vincenzo Librandi_, Dec 12 2013 *)
%o A041155 (Magma) I:=[1, 3, 55, 168]; [n le 4 select I[n] else 56*Self(n-2)-Self(n-4): n in [1..40]]; // _Vincenzo Librandi_, Dec 12 2013
%Y A041155 Cf. A041154.
%K A041155 nonn,frac,easy
%O A041155 0,2
%A A041155 _N. J. A. Sloane_