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 A277502 #8 Nov 13 2017 02:45:09
%S A277502 0,1,2,10,72,724,9184,142080,2587392,54290256,1289277440,34191270752,
%T A277502 1001513996288,32113767783616,1118831623585792,42084750888906240,
%U A277502 1699836383279448064,73377208318764134656,3371248736937012363264,164251735270613613412864
%N A277502 E.g.f.: -LambertW(-arcsin(x)).
%H A277502 G. C. Greubel, <a href="/A277502/b277502.txt">Table of n, a(n) for n = 0..385</a>
%F A277502 a(n) ~ sqrt(tan(exp(-1))) * exp(1/2 - n) * n^(n-1) / sin(exp(-1))^n.
%t A277502 CoefficientList[Series[-LambertW[-ArcSin[x]], {x, 0, 20}], x] * Range[0, 20]!
%o A277502 (PARI) x='x+O('x^30); concat([0], Vec(serlaplace(-lambertw(-asin(x))))) \\ _G. C. Greubel_, Nov 12 2017
%Y A277502 Cf. A277469, A277483, A277503.
%K A277502 nonn
%O A277502 0,3
%A A277502 _Vaclav Kotesovec_, Oct 18 2016