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A320806 Number of non-isomorphic multiset partitions of weight n in which each of the parts and each part of the dual, as well as both the multiset union of the parts and the multiset union of the dual parts, is an aperiodic multiset. 6
1, 1, 1, 4, 10, 39, 81, 343, 903, 3223, 9989 (list; graph; refs; listen; history; text; internal format)



Also the number of nonnegative integer matrices up to row and column permutations with sum of elements equal to n and no zero rows or columns, in which (1) the positive entries in each row and column are relatively prime and (2) the row sums and column sums are relatively prime.

The last condition (aperiodicity of the multiset union of the dual) is equivalent to the parts having relatively prime sizes.

A multiset is aperiodic if its multiplicities are relatively prime.

The dual of a multiset partition has, for each vertex, one part consisting of the indices (or positions) of the parts containing that vertex, counted with multiplicity. For example, the dual of {{1,2},{2,2}} is {{1},{1,2,2}}.

The weight of a multiset partition is the sum of sizes of its parts. Weight is generally not the same as number of vertices.


Table of n, a(n) for n=0..10.


Non-isomorphic representatives of the a(1) = 1 through a(4) = 10 multiset partitions:

  {{1}}  {{1},{2}}  {{1},{2,3}}    {{1},{2,3,4}}

                    {{2},{1,2}}    {{2},{1,2,2}}

                    {{1},{2},{2}}  {{3},{1,2,3}}

                    {{1},{2},{3}}  {{1},{1},{2,3}}








Cf. A000740, A000837, A007716, A007916, A100953, A301700, A303386, A303546, A303707, A303708, A316983, A320800-A320810, A321283.

Sequence in context: A149201 A065524 A024689 * A149202 A151447 A302183

Adjacent sequences:  A320803 A320804 A320805 * A320807 A320808 A320809




Gus Wiseman, Nov 07 2018



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Last modified July 8 04:16 EDT 2020. Contains 335504 sequences. (Running on oeis4.)