Number of symmetric short bushes with n edges.

Terms

a(0) =1a(1) =0a(2) =1a(3) =1a(4) =1a(5) =2a(6) =3a(7) =4a(8) =7a(9) =10a(10) =17a(11) =25a(12) =43a(13) =64a(14) =111a(15) =167a(16) =291a(17) =442a(18) =773a(19) =1183a(20) =2075a(21) =3196a(22) =5619a(23) =8702a(24) =15329a(25) =23852a(26) =42085a(27) =65755a(28) =116181a(29) =182186