Triangle of labeled mobiles (circular rooted trees) with n nodes and k leaves.

Terms

a(0) =1a(1) =2a(2) =0a(3) =6a(4) =3a(5) =0a(6) =24a(7) =36a(8) =8a(9) =0a(10) =120a(11) =360a(12) =220a(13) =30a(14) =0a(15) =720a(16) =3600a(17) =4200a(18) =1500a(19) =144a(20) =0a(21) =5040a(22) =37800a(23) =71400a(24) =47250a(25) =11508a(26) =840a(27) =0a(28) =40320a(29) =423360