Number of aperiodic rooted trees with n nodes.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =10a(6) =21a(7) =52a(8) =120a(9) =290a(10) =697a(11) =1713a(12) =4200a(13) =10446a(14) =26053a(15) =65473a(16) =165257a(17) =419357a(18) =1068239a(19) =2732509a(20) =7013242a(21) =18059960a(22) =46641983a(23) =120790324a(24) =313593621a(25) =816046050a(26) =2128101601a(27) =5560829666a(28) =14557746453a(29) =38177226541