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 A129393 #11 Apr 01 2023 18:08:56
%S A129393 1,5,-15,29,-23,-43,225,-499,601,197,-2991,8189,-12599,5045,35265,
%T A129393 -125971,236857,-206683,-327375,1808861,-4117079,5115797,1120929,
%U A129393 -23825971,66994201,-105678715,49059345,275536829,-1022847863,1966396277,-1807797375,-2442192979,14557768441
%N A129393 Row sums of A129392.
%C A129393 Also a diagonal close to the top of A129392.
%H A129393 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (-2, -1, 4).
%F A129393 Conjectures from _Colin Barker_, Oct 07 2015: (Start)
%F A129393 a(n) = -2*a(n-1) - a(n-2) + 4*a(n-3) for n>2.
%F A129393 G.f.: (4*x^2-7*x-1) / ((x-1)*(4*x^2+3*x+1)).
%F A129393 (End)
%t A129393 CoefficientList[Series[(4x^2-7x-1)/((x-1)(4x^2+3x+1)),{x,0,40}],x] (* or *) LinearRecurrence[{-2,-1,4},{1,5,-15},40] (* _Harvey P. Dale_, Apr 01 2023 *)
%Y A129393 Cf. A129392.
%K A129393 sign
%O A129393 0,2
%A A129393 _Jonas Wallgren_, Apr 13 2007
%E A129393 More terms from _R. J. Mathar_, Apr 30 2007