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 A041022 #30 Jul 14 2015 16:51:01
%S A041022 3,4,27,31,213,244,1677,1921,13203,15124,103947,119071,818373,937444,
%T A041022 6443037,7380481,50725923,58106404,399364347,457470751,3144188853,
%U A041022 3601659604,24754146477,28355806081
%N A041022 Numerators of continued fraction convergents to sqrt(15).
%H A041022 Vincenzo Librandi, <a href="/A041022/b041022.txt">Table of n, a(n) for n = 0..200</a>
%H A041022 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,8,0,-1).
%F A041022 G.f.: (3+4*x+3*x^2-x^3)/(1-8*x^2+x^4).
%F A041022 From _Gerry Martens_, Jul 11 2015: (Start)
%F A041022 Interspersion of 2 sequences [a0(n),a1(n)] for n>0:
%F A041022 a0(n) = (-((4-sqrt(15))^n*(3+sqrt(15)))+(-3+sqrt(15))*(4+sqrt(15))^n)/2.
%F A041022 a1(n) = ((4-sqrt(15))^n+(4+sqrt(15))^n)/2. (End)
%t A041022 Table[Numerator[FromContinuedFraction[ContinuedFraction[Sqrt[15],n]]],{n,1,50}] (* _Vladimir Joseph Stephan Orlovsky_, Mar 17 2011 *)
%t A041022 Numerator[Convergents[Sqrt[15], 30]] (* _Vincenzo Librandi_, Oct 28 2013 *)
%t A041022 a0[n_] := (-((4-Sqrt[15])^n*(3+Sqrt[15]))+(-3+Sqrt[15])*(4+Sqrt[15])^n)/2 // Simplify
%t A041022 a1[n_] := ((4-Sqrt[15])^n+(4+Sqrt[15])^n)/2 // Simplify
%t A041022 Flatten[MapIndexed[{a0[#], a1[#]} &,Range[20]]] (* _Gerry Martens_, Jul 11 2015 *)
%Y A041022 Cf. A010472, A041023.
%K A041022 nonn,cofr,frac,easy
%O A041022 0,1
%A A041022 _N. J. A. Sloane_