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A392771

a(n) = Sum_{k=0..n} |Stirling1(3*n,k)|.

1, 2, 394, 268028, 416636692, 1233511602464, 6262321994105824, 50704980188102965136, 618985065314184112929904, 10881560237703719303155190048, 265206328347178933976118431773600, 8682949789686716275225653540872628224, 371989791511233549949843753850230941197056

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..12.

FORMULA

a(n) ~ sqrt(2*Pi) * (3*n)^(3*n + 1/2) / exp(3*n).

MATHEMATICA

Table[Sum[Abs[StirlingS1[3*n, k]], {k, 0, n}], {n, 0, 12}]

PROG

(PARI) a(n) = sum(k=0, n, abs(stirling(3*n, k, 1))); \\ Michel Marcus, Jan 22 2026

CROSSREFS