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 A135258 #9 Oct 05 2016 02:40:49
%S A135258 0,1,-1,2,-3,7,-14,29,-57,114,-227,455,-910,1821,-3641,7282,-14563,
%T A135258 29127,-58254,116509,-233017,466034,-932067,1864135,-3728270,7456541,
%U A135258 -14913081,29826162,-59652323,119304647,-238609294,477218589,-954437177,1908874354
%N A135258 Inverse binomial transform of A131666 after removing A131666(0) = 0.
%C A135258 The inverse binomial transform generally equals the sequence of first terms of the iterated differences (i.e., equals the diagonal of the arrangement in the standard hand-written display of the differences).
%H A135258 G. C. Greubel, <a href="/A135258/b135258.txt">Table of n, a(n) for n = 0..1000</a>
%H A135258 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (-2,0,1,2).
%F A135258 O.g.f.: x*(1 + x)/((x^2 +x +1)*(1 +2*x)*(1-x)). - _R. J. Mathar_, Jul 22 2008
%F A135258 a(n) = -2*a(n-1) + a(n-3) + 2*a(n-4). - _G. C. Greubel_, Oct 04 2016
%t A135258 LinearRecurrence[{-2, 0, 1, 2}, {0, 1, -1, 2}, 50] (* _G. C. Greubel_, Oct 04 2016 *)
%o A135258 (PARI) concat(0, Vec(x*(1 + x)/((x^2 +x +1)*(1 +2*x)*(1-x)) + O(x^50))) \\ _Michel Marcus_, Oct 05 2016
%Y A135258 Cf. A113405.
%K A135258 sign
%O A135258 0,4
%A A135258 _Paul Curtz_, Dec 01 2007
%E A135258 Edited and corrected by _R. J. Mathar_, Jul 22 2008