Numbers whose base-11 representation has the same nonzero number of 4's and 7's.

Terms

a(0) =51a(1) =81a(2) =172a(3) =202a(4) =293a(5) =323a(6) =414a(7) =444a(8) =491a(9) =502a(10) =513a(11) =524a(12) =546a(13) =557a(14) =561a(15) =562a(16) =563a(17) =564a(18) =566a(19) =567a(20) =569a(21) =570a(22) =571a(23) =579a(24) =590a(25) =601a(26) =656a(27) =686a(28) =777a(29) =807