Number of n-node rooted unlabeled trees with outdegree <= 2 and exactly 1 edge at the root.

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =2a(5) =3a(6) =6a(7) =11a(8) =23a(9) =46a(10) =98a(11) =207a(12) =451a(13) =983a(14) =2179a(15) =4850a(16) =10905a(17) =24631a(18) =56011a(19) =127912a(20) =293547a(21) =676157a(22) =1563372a(23) =3626149a(24) =8436379a(25) =19680277a(26) =46026618a(27) =107890609a(28) =253450711a(29) =596572387