

A283877


Number of nonisomorphic setsystems of weight n.


7




OFFSET

1,2


COMMENTS

A setsystem is a finite set of finite nonempty sets. The weight of a setsystem is the sum of cardinalities of its elements.


LINKS

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


EXAMPLE

Nonisomorphic representatives of the a(4)=9 setsystems are:
((1234)),
((1)(234)), ((3)(123)), ((12)(34)), ((13)(23)),
((1)(2)(12)), ((1)(2)(34)), ((1)(3)(23)),
((1)(2)(3)(4)).


CROSSREFS

Cf. A007716, A034691, A049311, A056156, A089259, A116540.
Sequence in context: A259803 A032175 A000678 * A081490 A292478 A262864
Adjacent sequences: A283874 A283875 A283876 * A283878 A283879 A283880


KEYWORD

nonn,more


AUTHOR

Gus Wiseman, Mar 17 2017


STATUS

approved



