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 A319173 #5 Sep 14 2018 14:29:08
%S A319173 1,-1,2,-3,0,30,-240,1470,-6720,12600,214200,-4019400,45460800,
%T A319173 -378378000,1727926200,16358542200,-608230022400,10777315348800,
%U A319173 -137136749349600,1088994283977600,4431653341315200,-412892994284971200,10654104643073892000,-189834731018203471200
%N A319173 Expansion of e.g.f. 1/(1 + x/(1 + (x^2/2!)/(1 + (x^3/3!)/(1 + (x^4/4!)/(1 + ...))))), a continued fraction.
%t A319173 nmax = 23; CoefficientList[Series[1/(1 + ContinuedFractionK[x^k/k!, 1, {k, 1, nmax}]), {x, 0, nmax}], x] Range[0, nmax]!
%Y A319173 Cf. A007325, A257544, A295945.
%K A319173 sign
%O A319173 0,3
%A A319173 _Ilya Gutkovskiy_, Sep 12 2018