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A330464 Number of non-isomorphic weight-n sets of set-systems with distinct multiset unions. 0
1, 1, 3, 9, 32, 111, 463, 1942 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
COMMENTS
A set-system is a finite set of finite nonempty sets of positive integers.
As an alternative description, a(n) is the number of non-isomorphic sets of sets of sets with n leaves where the inner sets of sets all have different multiset unions.
LINKS
EXAMPLE
Non-isomorphic representatives of the a(1) = 1 through a(3) = 9 sets:
{} {{{1}}} {{{1,2}}} {{{1,2,3}}}
{{{1},{2}}} {{{1},{1,2}}}
{{{1}},{{2}}} {{{1},{2,3}}}
{{{1}},{{1,2}}}
{{{1}},{{2,3}}}
{{{1},{2},{3}}}
{{{1}},{{1},{2}}}
{{{1}},{{2},{3}}}
{{{1}},{{2}},{{3}}}
CROSSREFS
Non-isomorphic sets of sets are A283877.
Non-isomorphic sets of sets of sets are A323790.
Non-isomorphic set partitions of set-systems are A323795.
Sequence in context: A148976 A148977 A202143 * A148978 A148979 A148980
KEYWORD
nonn,more
AUTHOR
Gus Wiseman, Dec 26 2019
STATUS
approved

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Last modified March 19 04:58 EDT 2024. Contains 370952 sequences. (Running on oeis4.)