Number of uniform relatively prime rooted trees with n nodes.

Terms

a(0) =1a(1) =1a(2) =2a(3) =4a(4) =7a(5) =13a(6) =27a(7) =55a(8) =125a(9) =278a(10) =650a(11) =1510a(12) =3624a(13) =8655a(14) =21017a(15) =51212a(16) =125857a(17) =310581a(18) =770767a(19) =1920226