Odd digits in increasing order.

Terms

a(0) =1a(1) =3a(2) =5a(3) =7a(4) =9a(5) =13a(6) =15a(7) =17a(8) =19a(9) =35a(10) =37a(11) =39a(12) =57a(13) =59a(14) =79a(15) =135a(16) =137a(17) =139a(18) =157a(19) =159a(20) =179a(21) =357a(22) =359a(23) =379a(24) =579a(25) =1357a(26) =1359a(27) =1379a(28) =1579a(29) =3579