A318532 - OEIS

%I #5 Aug 29 2018 16:49:30

%S 2,4,11,51,635,15591

%N Number of finite sets of set partitions of {1,...,n} such that any two have meet {{1},...,{n}} and join {{1,...,n}}.

%e The a(3) = 11 sets of set partitions:

%e         0

%e     {{1,2,3}}

%e    {{1,3},{2}}

%e    {{1,2},{3}}

%e    {{1},{2,3}}

%e   {{1},{2},{3}}

%e    {{1,2},{3}}   {{1,3},{2}}

%e    {{1},{2,3}}   {{1,3},{2}}

%e    {{1},{2,3}}   {{1,2},{3}}

%e   {{1},{2},{3}}   {{1,2,3}}

%e    {{1},{2,3}}   {{1,2},{3}}  {{1,3},{2}}

%Y Cf. A000110, A000258, A008277, A059849, A060639, A096827, A181939.

%Y Cf. A318389, A318390, A318391, A318392, A318394, A318531.

%K nonn,more

%O 1,1

%A _Gus Wiseman_, Aug 28 2018