Number of trees on n nodes with 3 forbidden limbs of size 4, 5 and 6.

Terms

a(0) =0a(1) =1a(2) =1a(3) =2a(4) =3a(5) =6a(6) =12a(7) =30a(8) =67a(9) =159a(10) =381a(11) =929a(12) =2282a(13) =5680a(14) =14241a(15) =36009a(16) =91611a(17) =234512a(18) =603330a(19) =1559582a(20) =4047956a(21) =10546556a(22) =27570983a(23) =72301171a(24) =190136444a(25) =501323021a(26) =1324981299a(27) =3509660618a(28) =9315633928a(29) =24773632117