Numbers whose decimal expansion contains only 0's and 3's.

Terms

a(0) =0a(1) =3a(2) =30a(3) =33a(4) =300a(5) =303a(6) =330a(7) =333a(8) =3000a(9) =3003a(10) =3030a(11) =3033a(12) =3300a(13) =3303a(14) =3330a(15) =3333a(16) =30000a(17) =30003a(18) =30030a(19) =30033a(20) =30300a(21) =30303a(22) =30330a(23) =30333a(24) =33000a(25) =33003a(26) =33030a(27) =33033a(28) =33300a(29) =33303