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 A181658 #8 Mar 29 2022 12:20:33
%S A181658 1,2,3,7,8,19,20,48,49,118,119,287,288,695,696,1680,1681,4058,4059,
%T A181658 9799,9800,23659,23660,57120,57121,137902,137903,332927,332928,803759,
%U A181658 803760,1940448,1940449,4684658,4684659,11309767,11309768,27304195,27304196
%N A181658 Row sums of A181657.
%H A181658 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,3,0,-1,0,-1)
%F A181658 G.f.: (1+2x+x^3)/(1-3x^2+x^4+x^6)=(1+2x+x^3)/((1-x^2)(1-2x^2-x^4)).
%t A181658 CoefficientList[Series[(1+2x+x^3)/(1-3x^2+x^4+x^6),{x,0,40}],x] (* or *) LinearRecurrence[{0,3,0,-1,0,-1},{1,2,3,7,8,19},40] (* _Harvey P. Dale_, Mar 29 2022 *)
%Y A181658 Cf. A048739 (bisection).
%K A181658 easy,nonn
%O A181658 0,2
%A A181658 _Paul Barry_, Nov 03 2010