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 A130845 #19 May 06 2021 12:14:53
%S A130845 0,0,0,1,1,1,1,3,2,2,2,5,3,3,3,7,4,4,4,9,5,5,5,11,6,6,6,13,7,7,7,15,8,
%T A130845 8,8,17,9,9,9,19,10,10,10,21,11,11,11,23,12,12,12,25,13,13,13,27,14,
%U A130845 14,14,29,15,15,15,31,16,16,16,33,17,17,17
%N A130845 a(4n) = a(4n+1) = a(4n+2) = A001477(n), a(4n+3) = A005408(n).
%H A130845 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,2,0,0,0,-1).
%F A130845 O.g.f.: x^3*(1+x+x^2+x^3+x^4)/((1-x)^2*(1+x)^2*(1+x^2)^2). - _R. J. Mathar_, Aug 22 2008
%F A130845 a(0)=0, a(1)=0, a(2)=0, a(3)=1, a(4)=1, a(5)=1, a(6)=1, a(7)=3, a(n)=2*a(n-4)- a(n-8). - _Harvey P. Dale_, Mar 04 2012
%F A130845 a(n) = cos(n*Pi/2)/4-(n-1)*(2*sin(n*Pi/2)+(-1)^n-5)/16. - _Wesley Ivan Hurt_, May 05 2021
%t A130845 CoefficientList[Series[x^3(1+x+x^2+x^3+x^4)/((1-x)^2(1+x)^2(1+x^2)^2),{x,0,80}],x] (* or *) LinearRecurrence[{0,0,0,2,0,0,0,-1},{0,0,0,1,1,1,1,3},80] (* _Harvey P. Dale_, Mar 04 2012 *)
%K A130845 nonn
%O A130845 0,8
%A A130845 _Paul Curtz_, Jul 20 2007
%E A130845 Edited by _N. J. A. Sloane_, Sep 28 2007