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) =28a(8) =64a(9) =152a(10) =363a(11) =883a(12) =2165a(13) =5375a(14) =13439a(15) =33885a(16) =85960a(17) =219398a(18) =562768a(19) =1450356a(20) =3753054a(21) =9748390a(22) =25406262a(23) =66419263a(24) =174128256a(25) =457690900a(26) =1205900244a(27) =3184274398a(28) =8425557609a(29) =22336457078