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 A140883 #6 Sep 12 2013 15:53:56
%S A140883 2,1,1,1,0,1,4,-3,-3,4,9,0,-16,0,9,16,5,-20,-20,5,16,31,0,-30,0,-30,0,
%T A140883 31,64,-7,-112,56,56,-112,-7,64,129,0,-288,0,320,0,-288,0,129,256,9,
%U A140883 -576,-120,432,432,-120,-576,9,256,511,0,-1230,0,720,0,720,0,-1230,0,511
%N A140883 Triangle T(n,k) = A053120(n,k)+A053120(n,n-k) of symmetrized Chebyshev coefficients, read by rows, 0<=k<=n.
%C A140883 Row sums are constantly two.
%F A140883 T(n,k) = T(n,n-k).
%e A140883 2;
%e A140883 1, 1;
%e A140883 1, 0, 1;
%e A140883 4, -3, -3, 4;
%e A140883 9, 0, -16, 0, 9;
%e A140883 16, 5, -20, -20, 5, 16;
%e A140883 31, 0, -30, 0, -30, 0, 31;
%e A140883 64, -7, -112, 56, 56, -112, -7, 64;
%e A140883 129, 0, -288, 0, 320, 0, -288, 0, 129;
%e A140883 256, 9, -576, -120, 432, 432, -120, -576, 9, 256;
%e A140883 511, 0, -1230, 0, 720, 0, 720, 0, -1230, 0, 511;
%t A140883 Clear[p, x, n, m, a]; p[x_, n_] := ChebyshevT[n, x] + ExpandAll[x^n*ChebyshevT[n, 1/x]]; Table[p[x, n], {n, 0, 10}]; a = Table[CoefficientList[p[x, n], x], {n, 0, 10}]; Flatten[a]
%Y A140883 Cf. A053120.
%K A140883 tabl,sign
%O A140883 0,1
%A A140883 _Roger L. Bagula_ and _Gary W. Adamson_, Jul 22 2008