Symmetries in planted 3-trees on n+1 vertices.

Terms

a(0) =1a(1) =1a(2) =3a(3) =4a(4) =9a(5) =16a(6) =41a(7) =78a(8) =179a(9) =382a(10) =889a(11) =1992a(12) =4648a(13) =10749a(14) =25462a(15) =59891a(16) =142793a(17) =340761a(18) =819533a(19) =1975109a(20) =4784055a(21) =11617982a(22) =28316757a(23) =69185852a(24) =169516558a(25) =416268547a(26) =1024543728a(27) =2526631078a(28) =6242969248a(29) =15452300967