Number of 4-good trees with n nodes.

Terms

a(0) =1a(1) =1a(2) =2a(3) =6a(4) =25a(5) =140a(6) =1015a(7) =9065a(8) =95095a(9) =1131900a(10) =14964950a(11) =217091875a(12) =3430276850a(13) =58734600925