Number of rooted trees with a forbidden limb of length 6.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =9a(5) =20a(6) =47a(7) =113a(8) =281a(9) =706a(10) =1807a(11) =4671a(12) =12224a(13) =32247a(14) =85782a(15) =229683a(16) =618767a(17) =1675618a(18) =4559263a(19) =12457483a(20) =34168574a(21) =94040433a(22) =259637564a(23) =718892281a(24) =1995739380a(25) =5553867981a(26) =15490305017a(27) =43293762352a(28) =121235084565