Number of achiral trees with n nodes.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =5a(6) =7a(7) =14a(8) =21a(9) =40a(10) =61a(11) =118a(12) =186a(13) =355a(14) =567a(15) =1081a(16) =1755a(17) =3325a(18) =5454a(19) =10306a(20) =17070a(21) =32136a(22) =53628a(23) =100704a(24) =169175a(25) =316874a(26) =535267a(27) =1000524a(28) =1698322a(29) =3168500