Number of 3-covers of an unlabeled n-set.

Terms

a(0) =1a(1) =9a(2) =29a(3) =72a(4) =154a(5) =294a(6) =522a(7) =877a(8) =1406a(9) =2172a(10) =3255a(11) =4746a(12) =6763a(13) =9445a(14) =12953a(15) =17480a(16) =23254a(17) =30528a(18) =39604a(19) =50823a(20) =64568a(21) =81276a(22) =101443a(23) =125610a(24) =154395a(25) =188479a(26) =228611a(27) =275622a(28) =330432a(29) =394032