Number of Halin graphs on n unlabeled nodes.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =1a(5) =2a(6) =2a(7) =4a(8) =6a(9) =13a(10) =22a(11) =50a(12) =106a(13) =252a(14) =589a(15) =1475a(16) =3669a(17) =9435a(18) =24345a(19) =63837a(20) =168234a(21) =447562a(22) =1196390a(23) =3218221a(24) =8694411a(25) =23598318a(26) =64292975a(27) =175820236a(28) =482391019a(29) =1327680919