Triangle read by rows: T(n,k) = number of k-covers of a labeled n-set, k=1..2^n-1.

Terms

a(0) =1a(1) =1a(2) =3a(3) =1a(4) =1a(5) =12a(6) =32a(7) =35a(8) =21a(9) =7a(10) =1a(11) =1a(12) =39a(13) =321a(14) =1225a(15) =2919a(16) =4977a(17) =6431a(18) =6435a(19) =5005a(20) =3003a(21) =1365a(22) =455a(23) =105a(24) =15a(25) =1a(26) =1a(27) =120a(28) =2560a(29) =24990