Numbers whose base-10 representation has the same nonzero number of 3's and 9's.

Terms

a(0) =39a(1) =93a(2) =139a(3) =193a(4) =239a(5) =293a(6) =309a(7) =319a(8) =329a(9) =349a(10) =359a(11) =369a(12) =379a(13) =389a(14) =390a(15) =391a(16) =392a(17) =394a(18) =395a(19) =396a(20) =397a(21) =398a(22) =439a(23) =493a(24) =539a(25) =593a(26) =639a(27) =693a(28) =739a(29) =793