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A321678 Number of non-isomorphic weight-n strict antichains of sets with no singletons. 1
1, 0, 1, 1, 3, 3, 11, 13, 39, 67, 174 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

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

LINKS

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

EXAMPLE

Non-isomorphic representatives of the a(2) = 1 through a(6) = 11 antichains:

  {{1,2}}  {{1,2,3}}  {{1,2,3,4}}    {{1,2,3,4,5}}    {{1,2,3,4,5,6}}

                      {{1,2},{3,4}}  {{1,2},{3,4,5}}  {{1,2},{3,4,5,6}}

                      {{1,3},{2,3}}  {{1,4},{2,3,4}}  {{1,2,3},{4,5,6}}

                                                      {{1,2,5},{3,4,5}}

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

                                                      {{1,5},{2,3,4,5}}

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

                                                      {{1,2},{3,4},{5,6}}

                                                      {{1,2},{3,5},{4,5}}

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

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

CROSSREFS

Cf. A006126, A049311, A096827, A285572, A293993, A293994, A318099, A319719, A319721, A320799, A321679.

Sequence in context: A045495 A045494 A217712 * A027416 A281905 A278835

Adjacent sequences:  A321675 A321676 A321677 * A321679 A321680 A321681

KEYWORD

nonn,more

AUTHOR

Gus Wiseman, Nov 16 2018

STATUS

approved

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Last modified August 4 10:01 EDT 2021. Contains 346446 sequences. (Running on oeis4.)