Number of trees on n nodes with forbidden limbs.

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =1a(5) =1a(6) =2a(7) =6a(8) =10a(9) =20a(10) =44a(11) =93a(12) =207a(13) =468a(14) =1085a(15) =2533a(16) =6028a(17) =14447a(18) =35044a(19) =85603a(20) =210846a(21) =522471a(22) =1302878a(23) =3265540a(24) =8225968a(25) =20811621a(26) =52871283a(27) =134818074a(28) =344980825a(29) =885594103