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 A012960 #12 May 10 2020 13:42:48
%S A012960 1,2,3,2,-11,-30,175,1010,-6135,-60670,374875,5719650,-35199875,
%T A012960 -779710750,4687746375,145208599250,-836951243375,-35435177514750,
%U A012960 191995883837875,10975003189933250,-54688433347786875
%N A012960 Expansion of e.g.f. exp(arctan(x)+log(x+1)).
%F A012960 a(n) = (n*A002019(n)-A002019(n+1))/(n-1) for n > 1. [_Mark van Hoeij_, Jul 02 2010]
%e A012960 1+2*x+3/2!*x^2+2/3!*x^3-11/4!*x^4-30/5!*x^5...
%t A012960 With[{nn=20},CoefficientList[Series[Exp[ArcTan[x]+Log[x+1]],{x,0,nn}],x] Range[0,nn]!] (* _Harvey P. Dale_, Jul 25 2013 *)
%o A012960 (PARI) my(x='x+O('x^30)); Vec(serlaplace(exp(atan(x)+log(x+1)))) \\ _Michel Marcus_, May 10 2020
%Y A012960 Cf. A002019.
%K A012960 sign
%O A012960 0,2
%A A012960 Patrick Demichel (patrick.demichel(AT)hp.com)
%E A012960 Definition clarified by _Harvey P. Dale_, Jul 25 2013