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 A228470 #20 Dec 16 2023 16:59:19
%S A228470 3,11,18,68,111,419,684,2582,4215,15911,25974,98048,160059,604199,
%T A228470 986328,3723242,6078027,22943651,37454490,141385148,230804967,
%U A228470 871254539,1422284292,5368912382,8764510719,33084728831,54009348606,203877285368,332820602355
%N A228470 a(n) = 6*a(n-2) + a(n-4), where a(0) = 3, a(1) = 11, a(2) = 18, a(3) = 68.
%C A228470 Let d = A228469. Then a(n) is the least k > d(n) such that trace(k/d(n)) consists of the first n terms of 0101010101010101... See A228469.
%H A228470 Clark Kimberling, <a href="/A228470/b228470.txt">Table of n, a(n) for n = 0..1000</a>
%H A228470 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (0,6,0,1).
%e A228470 See A228469.
%t A228470 c1 = CoefficientList[Series[(2 + 8 x + x^2 + x^3)/(1 - 6 x^2 - x^4), {x, 0, 40}], x]; c2 = CoefficientList[Series[(3 + 11 x + 2 x^3)/(1 - 6 x^2 - x^4), {x, 0, 40}], x]; pairs = Transpose[CoefficientList[Series[{-((3 + 11 x + 2 x^3)/(-1 + 6 x^2 + x^4)), -((2 + 8 x + x^2 + x^3)/(-1 + 6 x^2 + x^4))}, {x, 0, 20}], x]]; t[{x_, y_, _}] := t[{x, y}]; t[{x_, y_}] := Prepend[If[# > y - #, {y - #, 1}, {#, 0}], y] &[Mod[x, y]]; userIn2[{x_, y_}] := Most[NestWhileList[t, {x, y}, (#[[2]] > 0) &]]; Map[Map[#[[3]] &, Rest[userIn2[#]]] &, pairs] (* _Peter J. C. Moses_, Aug 20 2013 *)
%t A228470 LinearRecurrence[{0, 6, 0, 1}, {3, 11, 18, 68}, 30] (* _T. D. Noe_, Aug 23 2013 *)
%Y A228470 Cf. A228469.
%K A228470 nonn
%O A228470 0,1
%A A228470 _Clark Kimberling_, Aug 22 2013