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 A157126 #7 Jun 13 2015 00:53:01
%S A157126 1,-2,-3,-3,8,11,11,-30,-41,-41,112,153,153,-418,-571,-571,1560,2131,
%T A157126 2131,-5822,-7953,-7953,21728,29681,29681,-81090,-110771,-110771,
%U A157126 302632,413403,413403,-1129438,-1542841,-1542841,4215120,5757961,5757961
%N A157126 Expansion of (1-2x-3x^2+x^3-x^5)/(1+4x^3+x^6).
%C A157126 Hankel transform of A157125.
%H A157126 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,-4,0,0,-1).
%F A157126 a(0)=1, a(1)=-2, a(2)=-3, a(3)=-3, a(4)=8, a(5)=11, a(n)=-4*a(n-3)-a(n-6). - _Harvey P. Dale_, Jan 16 2013
%t A157126 CoefficientList[Series[(1-2x-3x^2+x^3-x^5)/(1+4x^3+x^6),{x,0,40}],x] (* or *) LinearRecurrence[{0,0,-4,0,0,-1},{1,-2,-3,-3,8,11},40] (* _Harvey P. Dale_, Jan 16 2013 *)
%Y A157126 Cf. A048788.
%K A157126 easy,sign
%O A157126 0,2
%A A157126 _Paul Barry_, Feb 23 2009