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 A237993 #26 May 20 2025 08:11:39
%S A237993 1,2,274,118124,105258076,159721605680,369012649234384,
%T A237993 1206647803780373360,5304713715525445812976,
%U A237993 30180059720580991603896800,215760462268683520394805979744,1893448925578239663637174767335168,20012008248418194052035539503977759232
%N A237993 a(n) = |Stirling1(3*n,n)|.
%F A237993 a(n) ~ n^(2*n) * c^(3*n) * 3^(5*n) / (sqrt(6*Pi*(c-1)*n) * exp(2*n) * (3*c-1)^(2*n)), where c = -LambertW(-1,-exp(-1/3)/3) = 2.237147027773716818...
%F A237993 From _Seiichi Manyama_, May 20 2025: (Start)
%F A237993 a(n) = A132393(3*n,n).
%F A237993 a(n) = (3*n)! * [x^(3*n)] (-log(1 - x))^n / n!. (End)
%p A237993 seq(abs(Stirling1(3*n,n)), n=0..20);
%t A237993 Table[Abs[StirlingS1[3*n, n]],{n,0,20}]
%Y A237993 Cf. A132393, A187646, A242676, A217913.
%K A237993 nonn,easy
%O A237993 0,2
%A A237993 _Vaclav Kotesovec_, May 20 2014