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 A105398 #25 Dec 07 2019 12:18:24
%S A105398 4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,
%T A105398 4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,
%U A105398 4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4,8,4
%N A105398 A simple "Fractal Jump Sequence" (FJS).
%C A105398 See A105397 for definition of Fractal Jump Sequence.
%C A105398 Continued fraction expansion of (4+3*sqrt(2))/2. - _Bruno Berselli_, Nov 09 2011
%C A105398 Period 2: repeat [4, 8]. - _Wesley Ivan Hurt_, Feb 12 2017
%H A105398 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1).
%F A105398 G.f.: -4*x^4*(1+2*x) / ( (x-1)*(1+x) ). - _R. J. Mathar_, Jul 07 2011
%F A105398 a(n) = a(-n) = a(n-2) = 2*(3-(-1)^n) = 2^((5-(-1)^n)/2). - _Bruno Berselli_, Nov 09 2011
%p A105398 A105398:=n->2*(3-(-1)^n): seq(A105398(n), n=0..150); # _Wesley Ivan Hurt_, Feb 12 2017
%t A105398 PadRight[{}, 110, {4,8}] (* _Harvey P. Dale_, Nov 09 2011 *)
%o A105398 (Sage) [power_mod(2,n,12)for n in range(2,108)] # _Zerinvary Lajos_, Nov 03 2009
%o A105398 (Maxima) makelist(if evenp(n) then 4 else 8, n, 0, 30); /* _Martin Ettl_, Nov 12 2012 */
%Y A105398 Cf. A105397.
%K A105398 nonn,base,easy
%O A105398 4,1
%A A105398 _Eric Angelini_, May 01 2005