Number of trees on n nodes with forbidden limbs.

Terms

a(0) =0a(1) =1a(2) =2a(3) =5a(4) =18a(5) =70a(6) =282a(7) =1189a(8) =5144a(9) =22804a(10) =102908a(11) =471477a(12) =2186648a(13) =10247609a(14) =48449798a(15) =230819691a(16) =1106961890a(17) =5339801036a(18) =25891658674a(19) =126123321469a(20) =616916700222