Number of phylogenetic rooted trees with n unlabeled objects.

Terms

a(0) =1a(1) =2a(2) =4a(3) =11a(4) =30a(5) =96a(6) =308a(7) =1052a(8) =3648a(9) =13003a(10) =47006a(11) =172605a(12) =640662a(13) =2402388a(14) =9082538a(15) =34590673a(16) =132566826a(17) =510904724a(18) =1978728356a(19) =7697565819a(20) =30063818314a(21) =117840547815a(22) =463405921002