Number of unlabeled rooted trees with n nodes in which all outdegrees are either 0, 1, or 3.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =3a(5) =5a(6) =9a(7) =16a(8) =29a(9) =55a(10) =104a(11) =200a(12) =389a(13) =763a(14) =1507a(15) =3002a(16) =6010a(17) =12102a(18) =24484a(19) =49751a(20) =101475a(21) =207723a(22) =426542a(23) =878451a(24) =1813945a(25) =3754918a(26) =7790326a(27) =16196629a(28) =33739335a(29) =70410401