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A318402 Number of sets of nonempty sets whose multiset union is a strongly normal multiset of size n. 2
1, 2, 6, 20, 74, 311, 1401, 6913, 36376 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A multiset is strongly normal if it spans an initial interval of positive integers with weakly decreasing multiplicities.

LINKS

Table of n, a(n) for n=1..9.

EXAMPLE

The a(4) = 20 sets of sets:

  {{1,2,3,4}}

  {{1},{1,2,3}}

  {{1},{2,3,4}}

  {{2},{1,3,4}}

  {{3},{1,2,4}}

  {{4},{1,2,3}}

  {{1,2},{1,3}}

  {{1,2},{3,4}}

  {{1,3},{2,4}}

  {{1,4},{2,3}}

  {{1},{2},{1,2}}

  {{1},{2},{1,3}}

  {{1},{2},{3,4}}

  {{1},{3},{1,2}}

  {{1},{3},{2,4}}

  {{1},{4},{2,3}}

  {{2},{3},{1,4}}

  {{2},{4},{1,3}}

  {{3},{4},{1,2}}

  {{1},{2},{3},{4}}

CROSSREFS

Cf. A007716, A049311, A050326, A116540, A283877, A292432, A292444, A318361, A318369, A318370.

Sequence in context: A150158 A034010 A135588 * A293492 A150159 A150160

Adjacent sequences:  A318399 A318400 A318401 * A318403 A318404 A318405

KEYWORD

nonn,more

AUTHOR

Gus Wiseman, Aug 25 2018

STATUS

approved

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Last modified May 26 15:27 EDT 2020. Contains 334626 sequences. (Running on oeis4.)