Number of hierarchical orderings for n unlabeled elements with 2 possible classes for levels l>=2.

A104460

Number of hierarchical orderings for n unlabeled elements with 2 possible classes for levels l>=2.

Terms

    a(0) =1a(1) =4a(2) =13a(3) =46a(4) =154a(5) =533a(6) =1802a(7) =6137a(8) =20729a(9) =69971a(10) =235193a(11) =789000a(12) =2639004a(13) =8807811a(14) =29327841a(15) =97456878a(16) =323206002a(17) =1069923013a(18) =3535612108a(19) =11664423298a(20) =38422208659a(21) =126374059558a(22) =415069188175

External references