Numbers whose base-10 representation has the same nonzero number of 0's and 3's.

Terms

a(0) =30a(1) =103a(2) =130a(3) =203a(4) =230a(5) =301a(6) =302a(7) =304a(8) =305a(9) =306a(10) =307a(11) =308a(12) =309a(13) =310a(14) =320a(15) =340a(16) =350a(17) =360a(18) =370a(19) =380a(20) =390a(21) =403a(22) =430a(23) =503a(24) =530a(25) =603a(26) =630a(27) =703a(28) =730a(29) =803