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Number of different integer partitions of n that produce the maximum number of set partitions for a set of cardinality n.
1

%I #13 Sep 16 2019 19:54:48

%S 1,1,2,1,1,1,1,1,1,1,4,3,2,1,4,2,1,2,1,2,2,1,1,1,2,1,1,1,3,1,1,1,1,2,

%T 2,1,2,2,1,1,1,4,6,4,1,2,1,5,5,2,1,1,1,2,1,1,1,2,1,1,1,1,5,2,2,1,1,4,

%U 1,1,2,3,1,8,2,1,1,3,1,1,1,3,1,1,3,1,6,1,1,1,1,1,1,1,1,1,1,1,5,1,3,2,1,1,1,1

%N Number of different integer partitions of n that produce the maximum number of set partitions for a set of cardinality n.

%C If n=Sum_i[n_i], the number of set partitions can be written as sp=n!/Prod_i,j(n_i!m_j!) where m_j is the multiplicity of the integer j in the n_i's. For certain integers, this number is maximized by more than one partition.

%H Alois P. Heinz, <a href="/A255404/b255404.txt">Table of n, a(n) for n = 0..1000</a>

%e For n=9, {1,1,2,2,3} maximizes the number of set partitions, while for n=10, this number is maximized by {1,2,3,4}, {1,1,2,3,3}, {1,2,2,2,3} and {1,1,1,2,2,3}.

%t Prod[l_] := Apply[Times, Map[#! &, l]]*

%t Apply[Times, Map[Count[l, #]! &, Range[Max[Length[l]]]]]

%t b[n_] := (Min[Map[Prod, IntegerPartitions[n]]])

%t a[n_] := Count[Map[Prod, IntegerPartitions[n]], b[n]]

%t Table[a[n], {n, 0, 20}] (* after A102356 *)

%Y Cf. A102356, A102456.

%K nonn

%O 0,3

%A _Andrei Cretu_, Feb 22 2015

%E More terms from _Alois P. Heinz_, Feb 25 2015

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Last modified September 22 14:04 EDT 2024. Contains 376114 sequences. (Running on oeis4.)