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 A230011 #9 Dec 25 2013 02:37:54
%S A230011 1,0,1,-1,1,-1,3,-3,-11,11,113,-113,-1269,1269,20575,-20575,-888419,
%T A230011 888419,24729909,-24729909,-862992415,862992415,36913939753,
%U A230011 -36913939753,-1899853421901,1899853421901,115841483491307,-115841483491307
%N A230011 Numerators of sum of rows of the inverse of the triangle of Euler polynomial coefficients P(0,x)=1, 2P(n,x)=(1+x)*[(1+x)^(n-1)+x^(n-1)].
%C A230011 See A133135.
%C A230011 Denominators are 1, 1, 2, 2, 4, 4, 4, 4, 8, 8, 8, 8, 8, 8, 8, 8, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 32, 32, ..., a sequence which matches A053644, except the first term.
%e A230011 1, 0, 1/2, -1/2, 1/4, -1/4, 3/4, -3/4, -11/8, 11/8, 113/8, -113/8, ...
%t A230011 max = 30; p[0, _] = 1; p[n_, x_] := (1+x)*((1+x)^(n-1)+x^(n-1))/2; t = Total /@ Inverse @ Table[Coefficient[p[n, x], x, k], {n, 0, max+2}, {k, 0, max+2}]; a[n_] := t[[n+1]] // Numerator; Table[a[n], {n, 0, max}]
%Y A230011 Cf. A053644, A133135.
%K A230011 sign,frac,easy
%O A230011 0,7
%A A230011 _Jean-François Alcover_ and _Paul Curtz_, Dec 20 2013