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A332944 Number of entries in the fourth blocks of all set partitions of [n] when blocks are ordered by increasing lengths. 2
1, 21, 166, 1247, 7855, 47245, 284968, 1741235, 10782872, 69537976, 471717130, 3336898255, 24584784957, 189704257763, 1530649634720, 12849873769593, 111945035887787, 1011184665775833, 9458811859041042, 91480934118104305, 913112230809837136, 9391472034599656856 (list; graph; refs; listen; history; text; internal format)
OFFSET

4,2

LINKS

Alois P. Heinz, Table of n, a(n) for n = 4..576

Wikipedia, Partition of a set

MAPLE

b:= proc(n, i, t) option remember; `if`(n=0, [1, 0], `if`(i>n, 0,

      add((p-> p+`if`(t>0 and t-j<1, [0, p[1]*i], 0))(b(n-i*j, i+1,

      max(0, t-j))/j!*combinat[multinomial](n, i$j, n-i*j)), j=0..n/i)))

    end:

a:= n-> b(n, 1, 4)[2]:

seq(a(n), n=4..25);

CROSSREFS

Column k=4 of A319298.

Sequence in context: A146301 A338891 A126993 * A022681 A266733 A107970

Adjacent sequences:  A332941 A332942 A332943 * A332945 A332946 A332947

KEYWORD

nonn

AUTHOR

Alois P. Heinz, Mar 03 2020

STATUS

approved

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Last modified August 12 23:52 EDT 2022. Contains 356077 sequences. (Running on oeis4.)