Number of unlabeled semi-identity plane trees with n nodes.

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =13a(5) =38a(6) =117a(7) =375a(8) =1224a(9) =4095a(10) =13925a(11) =48006a(12) =167259a(13) =588189a(14) =2084948a(15) =7442125a(16) =26725125a(17) =96485782a(18) =350002509a(19) =1275061385a(20) =4662936808a(21) =17111964241a(22) =62996437297a(23) =232589316700a(24) =861028450579