Number of pairs of partitions of [n] whose join is the partition {{1,2,...,n}}.

A060639

Number of pairs of partitions of [n] whose join is the partition {{1,2,...,n}}.

Terms

    a(0) =1a(1) =1a(2) =3a(3) =15a(4) =119a(5) =1343a(6) =19905a(7) =369113a(8) =8285261a(9) =219627683a(10) =6746244739a(11) =236561380795

External references