Number of rooted trees on n nodes with forbidden limbs.

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =4a(5) =9a(6) =20a(7) =47a(8) =112a(9) =279a(10) =701a(11) =1794a(12) =4636a(13) =12130a(14) =31987a(15) =85062a(16) =227673a(17) =613126a(18) =1659712a(19) =4514249a(20) =12329670a(21) =33804673a(22) =93001852a(23) =256667215a(24) =710381240a(25) =1971312184a(26) =5483656721a(27) =15288227949a(28) =42711458197a(29) =119555284629