OFFSET
1,2
COMMENTS
Also the number of non-isomorphic set multipartitions (multisets of sets) with n parts and n vertices. - Gus Wiseman, Nov 18 2018
LINKS
Andrew Howroyd, Table of n, a(n) for n = 1..50
EXAMPLE
From Gus Wiseman, Nov 18 2018: (Start)
Inequivalent representatives of the a(3) = 17 matrices:
100 100 100 100 100 010 010 001 001 001 001 110 101 101 011 011 111
100 010 001 011 011 001 101 001 101 011 111 101 011 011 011 111 111
011 001 011 011 111 111 011 111 011 111 111 011 011 111 111 111 111
Non-isomorphic representatives of the a(1) = 1 through a(3) = 17 set multipartitions:
{{1}} {{1},{2}} {{1},{2},{3}}
{{2},{1,2}} {{1},{1},{2,3}}
{{1,2},{1,2}} {{1},{3},{2,3}}
{{1},{2,3},{2,3}}
{{2},{1,3},{2,3}}
{{2},{3},{1,2,3}}
{{3},{1,3},{2,3}}
{{3},{3},{1,2,3}}
{{1,2},{1,3},{2,3}}
{{1},{2,3},{1,2,3}}
{{1,3},{2,3},{2,3}}
{{3},{2,3},{1,2,3}}
{{1,3},{2,3},{1,2,3}}
{{2,3},{2,3},{1,2,3}}
{{3},{1,2,3},{1,2,3}}
{{2,3},{1,2,3},{1,2,3}}
{{1,2,3},{1,2,3},{1,2,3}}
(End)
MATHEMATICA
a /@ Range[1, 13] (* Jean-François Alcover, Sep 14 2019 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, May 27 2000
EXTENSIONS
More terms from David Wasserman, Mar 06 2002
Terms a(14) and beyond from Andrew Howroyd, Apr 11 2020
STATUS
approved