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 A041121 #23 Jul 09 2025 00:17:58
%S A041121 1,3,10,13,62,75,287,936,15263,46725,155438,202163,964090,1166253,
%T A041121 4462849,14554800,237339649,726573747,2417060890,3143634637,
%U A041121 14991599438,18135234075,69397301663,226327139064,3690631526687,11298221719125,37585296684062,48883518403187
%N A041121 Denominators of continued fraction convergents to sqrt(69).
%H A041121 Vincenzo Librandi, <a href="/A041121/b041121.txt">Table of n, a(n) for n = 0..200</a>
%H A041121 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,15550,0,0,0,0,0,0,0,-1).
%F A041121 G.f.: -(x^14 -3*x^13 +10*x^12 -13*x^11 +62*x^10 -75*x^9 +287*x^8 -936*x^7 -287*x^6 -75*x^5 -62*x^4 -13*x^3 -10*x^2 -3*x -1) / (x^16 -15550*x^8 +1). - _Colin Barker_, Nov 13 2013
%F A041121 a(n) = 15550*a(n-8) - a(n-16). - _Vincenzo Librandi_, Dec 11 2013
%t A041121 Table[Denominator[FromContinuedFraction[ContinuedFraction[Sqrt[69],n]]],{n,1,50}] (* _Vladimir Joseph Stephan Orlovsky_, Jun 26 2011 *)
%t A041121 Denominator[Convergents[Sqrt[69], 30]] (* _Vincenzo Librandi_, Dec 11 2013 *)
%t A041121 LinearRecurrence[{0,0,0,0,0,0,0,15550,0,0,0,0,0,0,0,-1},{1,3,10,13,62,75,287,936,15263,46725,155438,202163,964090,1166253,4462849,14554800},30] (* _Harvey P. Dale_, Oct 18 2015 *)
%o A041121 (Magma) I:=[1, 3, 10, 13, 62, 75, 287, 936, 15263, 46725, 155438, 202163, 964090, 1166253, 4462849, 14554800]; [n le 16 select I[n] else 15550*Self(n-8)-Self(n-16): n in [1..40]]; // _Vincenzo Librandi_, Dec 11 2013
%Y A041121 Cf. A041120, A010148, A020826, A010521.
%K A041121 nonn,cofr,frac,easy
%O A041121 0,2
%A A041121 _N. J. A. Sloane_
%E A041121 More terms from _Colin Barker_, Nov 13 2013