Number of (<=2)-covers of an n-set.

A094574

Number of (<=2)-covers of an n-set.

Terms

    a(0) =1a(1) =1a(2) =5a(3) =40a(4) =457a(5) =6995a(6) =136771a(7) =3299218a(8) =95668354a(9) =3268445951a(10) =129468914524

External references