Number of identity trees with n nodes where the maximal outdegree (branching factor) equals 3.

Terms

a(0) =1a(1) =3a(2) =9a(3) =25a(4) =66a(5) =170a(6) =431a(7) =1076a(8) =2665a(9) =6560a(10) =16067a(11) =39219a(12) =95476a(13) =231970a(14) =562736a(15) =1363640a(16) =3301586a(17) =7988916a(18) =19322585a(19) =46722160a(20) =112955614a(21) =273063236a(22) =660116215a(23) =1595906490a(24) =3858740567a(25) =9331539319a(26) =22570697689a(27) =54605064084a(28) =132137719127a(29) =319841444030