Number of 2n-node rooted identity trees of height n.

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =8a(5) =34a(6) =149a(7) =672a(8) =3078a(9) =14232a(10) =66278a(11) =310408a(12) =1460390a(13) =6896417a(14) =32668860a(15) =155166468a(16) =738679240a(17) =3523549192a(18) =16837094932a(19) =80580576022a(20) =386187326865