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 A237993 a(n) = Abs(StirlingS1(3*n,n)). 2

%I

%S 1,2,274,118124,105258076,159721605680,369012649234384,

%T 1206647803780373360,5304713715525445812976,

%U 30180059720580991603896800,215760462268683520394805979744,1893448925578239663637174767335168,20012008248418194052035539503977759232

%N a(n) = Abs(StirlingS1(3*n,n)).

%F 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...

%p seq(abs(Stirling1(3*n,n)), n=0..20);

%t Table[Abs[StirlingS1[3*n, n]],{n,0,20}]

%Y Cf. A187646, A242676, A217913.

%K nonn,easy

%O 0,2

%A _Vaclav Kotesovec_, May 20 2014

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Last modified October 14 08:54 EDT 2019. Contains 327995 sequences. (Running on oeis4.)