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 A042415 #21 Jul 09 2025 02:45:42
%S A042415 1,9,487,4392,237655,2143287,115975153,1045919664,56595637009,
%T A042415 510406652745,27618554885239,249077400619896,13477798188359623,
%U A042415 121549261095856503,6577137897364610785,59315790337377353568,3209629816115741703457
%N A042415 Denominators of continued fraction convergents to sqrt(735).
%H A042415 Vincenzo Librandi, <a href="/A042415/b042415.txt">Table of n, a(n) for n = 0..200</a>
%H A042415 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (0,488,0,-1).
%F A042415 G.f.: -(x^2-9*x-1) / (x^4-488*x^2+1). - _Colin Barker_, Dec 12 2013
%t A042415 Denominator[Convergents[Sqrt[735], 20]] (* _Harvey P. Dale_, Oct 11 2011 *)
%t A042415 CoefficientList[Series[(1 + 9 x - x^2)/(x^4 - 488 x^2 + 1), {x, 0, 30}], x] (* _Vincenzo Librandi_, Jan 21 2014 *)
%Y A042415 Cf. A042414, A040707.
%K A042415 nonn,frac,easy
%O A042415 0,2
%A A042415 _N. J. A. Sloane_
%E A042415 More terms from _Colin Barker_, Dec 12 2013