Triangle of allowable Stirling numbers of the second kind a(n,k).

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =2a(5) =1a(6) =1a(7) =3a(8) =4a(9) =1a(10) =1a(11) =4a(12) =11a(13) =6a(14) =1a(15) =1a(16) =5a(17) =26a(18) =23a(19) =9a(20) =1a(21) =1a(22) =6a(23) =57a(24) =72a(25) =50a(26) =12a(27) =1a(28) =1a(29) =7