Number of rooted identity trees with n nodes and exactly 3 subtrees from the root.

Terms

a(0) =1a(1) =2a(2) =5a(3) =12a(4) =28a(5) =65a(6) =152a(7) =351a(8) =818a(9) =1907a(10) =4460a(11) =10453a(12) =24581a(13) =57922a(14) =136860a(15) =324088a(16) =769188a(17) =1829282a(18) =4359048a(19) =10406106a(20) =24885240a(21) =59607192a(22) =142996100a(23) =343540150a(24) =826468374a(25) =1990841497a(26) =4801534221a(27) =11593858684a(28) =28025623617a(29) =67816875039