Number of achiral planted trees with n nodes.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =5a(6) =8a(7) =14a(8) =23a(9) =41a(10) =69a(11) =122a(12) =208a(13) =370a(14) =636a(15) =1134a(16) =1963a(17) =3505a(18) =6099a(19) =10908a(20) =19059a(21) =34129a(22) =59836a(23) =107256a(24) =188576a(25) =338322a(26) =596252a(27) =1070534a(28) =1890548a(29) =3396570