Number of "peerless" trees on n nodes.

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =2a(5) =3a(6) =6a(7) =9a(8) =19a(9) =33a(10) =67a(11) =130a(12) =270a(13) =547a(14) =1165a(15) =2456a(16) =5314a(17) =11521a(18) =25357a(19) =56022a(20) =125067a(21) =280471a(22) =633490a(23) =1437340a(24) =3278912a(25) =7510503a(26) =17277697a(27) =39890262a(28) =92427559a(29) =214835923