Number of ordered bicoverings of an unlabeled n-set.
A060090
Number of ordered bicoverings of an unlabeled n-set.
Terms
- a(0) =1a(1) =0a(2) =3a(3) =23a(4) =290a(5) =4298a(6) =79143a(7) =1702923a(8) =42299820a(9) =1188147639a(10) =37276597020
External references
- oeis: A060090