Triangle T(n,k) of numbers of k-covers of an unlabeled n-set, k=1..2^n-1.

Terms

a(0) =1a(1) =1a(2) =2a(3) =1a(4) =1a(5) =4a(6) =9a(7) =10a(8) =6a(9) =3a(10) =1a(11) =1a(12) =7a(13) =29a(14) =87a(15) =181a(16) =287a(17) =364a(18) =365a(19) =290a(20) =187a(21) =97a(22) =39a(23) =13a(24) =4a(25) =1a(26) =1a(27) =10a(28) =72a(29) =417