Number of n-node rooted trees of height 3.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =3a(5) =8a(6) =18a(7) =38a(8) =76a(9) =147a(10) =277a(11) =509a(12) =924a(13) =1648a(14) =2912a(15) =5088a(16) =8823a(17) =15170a(18) =25935a(19) =44042a(20) =74427a(21) =125112a(22) =209411a(23) =348960a(24) =579326a(25) =958077a(26) =1579098a(27) =2593903a(28) =4247768a(29) =6935070