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%I #12 Jan 22 2026 13:25:27
%S 1,2,394,268028,416636692,1233511602464,6262321994105824,
%T 50704980188102965136,618985065314184112929904,
%U 10881560237703719303155190048,265206328347178933976118431773600,8682949789686716275225653540872628224,371989791511233549949843753850230941197056
%N a(n) = Sum_{k=0..n} |Stirling1(3*n,k)|.
%F a(n) ~ sqrt(2*Pi) * (3*n)^(3*n + 1/2) / exp(3*n).
%t Table[Sum[Abs[StirlingS1[3*n, k]], {k, 0, n}], {n, 0, 12}]
%o (PARI) a(n) = sum(k=0, n, abs(stirling(3*n,k,1))); \\ _Michel Marcus_, Jan 22 2026
%Y Cf. A008275, A349783, A392772, A357828.
%K nonn
%O 0,2
%A _Vaclav Kotesovec_, Jan 22 2026