Numbers whose base-10 representation has the same nonzero number of 0's and 7's.

Terms

a(0) =70a(1) =107a(2) =170a(3) =207a(4) =270a(5) =307a(6) =370a(7) =407a(8) =470a(9) =507a(10) =570a(11) =607a(12) =670a(13) =701a(14) =702a(15) =703a(16) =704a(17) =705a(18) =706a(19) =708a(20) =709a(21) =710a(22) =720a(23) =730a(24) =740a(25) =750a(26) =760a(27) =780a(28) =790a(29) =807