login

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).

Number of triples of set partitions of {1,...,n} with meet {{1},...,{n}} and join {{1,...,n}}.
3

%I #5 Aug 27 2018 22:34:19

%S 1,6,84,2226,93246,5616492,459173406,48933260388,6595445513412,

%T 1098326915060730,221772386369110242,53460963703982862534,

%U 15185890964240671486740,5026315912246843181692776,1919721040169845172603949966,838872819016448052585038291124

%N Number of triples of set partitions of {1,...,n} with meet {{1},...,{n}} and join {{1,...,n}}.

%F Logarithmic transform of A318398.

%e The a(2) = 6 triples:

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

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

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

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

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

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

%t nn=20;

%t Table[n!*SeriesCoefficient[Log[1+Sum[x^k/k!*Sum[StirlingS1[k,i]*BellB[i]^3,{i,0,k}],{k,nn}]],{x,0,n}],{n,nn}]

%Y Cf. A000110, A000258, A001247, A008277, A048994, A059849, A060639, A181939, A318389, A318390, A318391, A318392, A318393, A318398.

%K nonn

%O 1,2

%A _Gus Wiseman_, Aug 25 2018