a(n) = 2^phi(n)+1 = A066781(n)+1.

Terms

a(0) =3a(1) =3a(2) =5a(3) =5a(4) =17a(5) =5a(6) =65a(7) =17a(8) =65a(9) =17a(10) =1025a(11) =17a(12) =4097a(13) =65a(14) =257a(15) =257a(16) =65537a(17) =65a(18) =262145a(19) =257a(20) =4097a(21) =1025a(22) =4194305a(23) =257a(24) =1048577a(25) =4097a(26) =262145a(27) =4097a(28) =268435457a(29) =257