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 A309254 #27 Aug 09 2019 02:55:01 %S A309254 1,1,1,-1,1,1,-11,41,-83,-77,1621,-8503,25689,-11283,-436307,3380827, %T A309254 -15378675,37938353,87204085,-1755462619,12722279385,-61250294425, %U A309254 164643256457,465385122833,-10366591960879,88472237039417,-527994960273655,2118908595206935,-1118896610239543 %N A309254 Shifts left by 2 places under series reversion. %C A309254 Series reversion of the g.f. gives the same sequence with two initial terms (1, 1) dropped. %F A309254 G.f. satisfies A((A(x) - x - x^2)/x^2) = x. %t A309254 Nest[InverseSeries[#] x^2 + x^2 + x &, x + O[x]^2, 14][[3]] %Y A309254 Cf. A067145, A309564. %K A309254 sign %O A309254 1,7 %A A309254 _Vladimir Reshetnikov_, Aug 07 2019