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 A037688 #9 Mar 06 2024 16:45:59
%S A037688 1,6,24,99,397,1590,6360,25443,101773,407094,1628376,6513507,26054029,
%T A037688 104216118,416864472,1667457891,6669831565,26679326262,106717305048,
%U A037688 426869220195,1707476880781,6829907523126,27319630092504
%N A037688 Base-4 digits are, in order, the first n terms of the periodic sequence with initial period 1,2,0,3.
%H A037688 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (4,0,0,1,-4).
%F A037688 G.f.: ( x*(1+2*x+3*x^3) ) / ( (x-1)*(4*x-1)*(1+x)*(x^2+1) ). - _R. J. Mathar_, Oct 11 2015
%t A037688 Table[FromDigits[PadRight[{},n,{1,2,0,3}],4],{n,30}] (* _Harvey P. Dale_, Mar 06 2024 *)
%K A037688 nonn,base,easy
%O A037688 1,2
%A A037688 _Clark Kimberling_