Number of multiple hierarchies for n labeled elements.

A143463

Number of multiple hierarchies for n labeled elements.

Terms

    a(0) =1a(1) =4a(2) =20a(3) =133a(4) =1047a(5) =9754a(6) =103203a(7) =1229330a(8) =16198452a(9) =234110702a(10) =3675679471a(11) =62287376870

External references