Numbers whose set of base-4 digits is a subset of {1,3}.

Terms

a(0) =1a(1) =3a(2) =5a(3) =7a(4) =13a(5) =15a(6) =21a(7) =23a(8) =29a(9) =31a(10) =53a(11) =55a(12) =61a(13) =63a(14) =85a(15) =87a(16) =93a(17) =95a(18) =117a(19) =119a(20) =125a(21) =127a(22) =213a(23) =215a(24) =221a(25) =223a(26) =245a(27) =247a(28) =253a(29) =255