Number of unlabeled rooted trees with n nodes and maximal outdegree (branching factor) 2.

Terms

a(0) =1a(1) =2a(2) =5a(3) =10a(4) =22a(5) =45a(6) =97a(7) =206a(8) =450a(9) =982a(10) =2178a(11) =4849a(12) =10904a(13) =24630a(14) =56010a(15) =127911a(16) =293546a(17) =676156a(18) =1563371a(19) =3626148a(20) =8436378a(21) =19680276a(22) =46026617a(23) =107890608a(24) =253450710a(25) =596572386a(26) =1406818758a(27) =3323236237a(28) =7862958390a(29) =18632325318