Number of series-reduced palindromic plane trees with n nodes.

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =1a(5) =2a(6) =3a(7) =4a(8) =7a(9) =10a(10) =15a(11) =23a(12) =35a(13) =52a(14) =81a(15) =121a(16) =185a(17) =280a(18) =427a(19) =645a(20) =985a(21) =1490a(22) =2269a(23) =3440a(24) =5233a(25) =7936a(26) =12071a(27) =18313a(28) =27839a(29) =42256