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 A089076 #21 Dec 24 2022 02:35:56
%S A089076 -1,0,-2,2,-4,4,-6,7,-11,14,-20,26,-37,50,-70,95,-132,181,-251,345,
%T A089076 -477,657,-908,1252,-1729,2385,-3293,4544,-6273,8657,-11950,16493,
%U A089076 -22766,31422,-43372,59864,-82630,114051,-157423,217286,-299916,413966,-571389,788674,-1088590,1502555,-2073944,2862617
%N A089076 Expansion of -x - x^3*(2 -2*x^4 +x^5)/((1-x^2)*(1+x+x^4)).
%H A089076 G. C. Greubel, <a href="/A089076/b089076.txt">Table of n, a(n) for n = 1..1000</a>
%H A089076 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (-1,1,1,1,0,-1).
%F A089076 G.f.: -x - x^3*(2 -2*x^4 +x^5)/((1-x^2)*(1+x+x^4)).
%t A089076 Rest@CoefficientList[Series[-x -x^3*(2-2*x^4+x^5)/((1-x^2)*(1+x-x^4)), {x,0,50}], x] (* _G. C. Greubel_, Feb 19 2021 *)
%t A089076 LinearRecurrence[{-1,1,1,1,0,-1},{-1,0,-2,2,-4,4,-6,7},50] (* _Harvey P. Dale_, Aug 11 2021 *)
%o A089076 (Sage)
%o A089076 def A089076_list(prec):
%o A089076 P.<x> = PowerSeriesRing(ZZ, prec)
%o A089076 return P( -x -x^3*(2-2*x^4+x^5)/((1-x^2)*(1+x-x^4)) ).list()
%o A089076 a=A089076_list(51); a[1:] # _G. C. Greubel_, Feb 19 2021
%o A089076 (Magma)
%o A089076 R<x>:=PowerSeriesRing(Integers(), 50);
%o A089076 Coefficients(R!( -x -x^3*(2-2*x^4+x^5)/((1-x^2)*(1+x-x^4)) )); // _G. C. Greubel_, Feb 19 2021
%Y A089076 Cf. A089074, A089075, A089077.
%K A089076 sign
%O A089076 1,3
%A A089076 _Roger L. Bagula_, Dec 04 2003
%E A089076 Edited by _G. C. Greubel_, Feb 19 2021