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A327505 Number of set partitions of [n] where each subset is again partitioned into four nonempty subsets. 2
1, 0, 0, 0, 1, 10, 65, 350, 1736, 9030, 60355, 561550, 6183221, 69469400, 761767370, 8239194600, 91058524831, 1073790441370, 13900626022985, 196759304278250, 2963381404815566, 46227649788125190, 736940002561065325, 12005645243802471250, 201482801573414254301 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..495

Wikipedia, Partition of a set

FORMULA

E.g.f.: exp((exp(x)-1)^4/4!).

MAPLE

a:= proc(n) option remember; `if`(n=0, 1, add(a(n-j)

      *binomial(n-1, j-1)*Stirling2(j, 4), j=4..n))

    end:

seq(a(n), n=0..25);

CROSSREFS

Column k=4 of A324162.

Sequence in context: A003519 A056280 A000453 * A291231 A097791 A212259

Adjacent sequences:  A327502 A327503 A327504 * A327506 A327507 A327508

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Sep 14 2019

STATUS

approved

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Last modified September 28 17:43 EDT 2020. Contains 337393 sequences. (Running on oeis4.)