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 A078041 #13 Aug 08 2019 18:58:33
%S A078041 1,-2,3,-3,2,1,-5,10,-13,13,-6,-7,27,-46,59,-51,18,49,-133,218,-253,
%T A078041 205,-22,-279,667,-990,1099,-755,-126,1569,-3205,4522,-4589,2701,1754,
%U A078041 -8231,15387,-20110,19035,-8371,-12814,42513,-72069,88954,-75997,20813,81098,-212279,335003,-385086,295531
%N A078041 Expansion of (1-x)/(1+x-x^2-2*x^3).
%H A078041 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-1,1,2).
%t A078041 CoefficientList[Series[(1-x)/(1+x-x^2-2x^3),{x,0,60}],x] (* or *) LinearRecurrence[{-1,1,2},{1,-2,3},60] (* _Harvey P. Dale_, Dec 03 2018 *)
%Y A078041 First differences of A077971.
%K A078041 sign,easy
%O A078041 0,2
%A A078041 _N. J. A. Sloane_, Nov 17 2002