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 A041391 #19 Jul 09 2025 00:45:25 %S A041391 1,2,57,116,3305,6726,191633,389992,11111409,22612810,644270089, %T A041391 1311152988,37356553753,76024260494,2166035847585,4408095955664, %U A041391 125592722606177,255593541168018,7282211875310681,14820017291789380,422242696045413321 %N A041391 Denominators of continued fraction convergents to sqrt(210). %H A041391 Vincenzo Librandi, <a href="/A041391/b041391.txt">Table of n, a(n) for n = 0..200</a> %H A041391 <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (0,58,0,-1). %F A041391 G.f.: -(x^2-2*x-1) / (x^4-58*x^2+1). - _Colin Barker_, Nov 17 2013 %F A041391 a(n) = 58*a(n-2) - a(n-4) for n>3. - _Vincenzo Librandi_, Dec 17 2013 %t A041391 Denominator[Convergents[Sqrt[210], 30]] (* _Vincenzo Librandi_, Dec 17 2013 *) %o A041391 (Magma) I:=[1,2,57,116]; [n le 4 select I[n] else 58*Self(n-2)-Self(n-4): n in [1..40]]; // _Vincenzo Librandi_, Dec 17 2013 %Y A041391 Cf. A041390, A176441, A040195. %K A041391 nonn,frac,easy %O A041391 0,2 %A A041391 _N. J. A. Sloane_ %E A041391 More terms from _Colin Barker_, Nov 17 2013