Numbers whose base-7 representation has the same nonzero number of 1's and 4's.

Terms

a(0) =11a(1) =29a(2) =53a(3) =67a(4) =74a(5) =77a(6) =79a(7) =80a(8) =82a(9) =83a(10) =88a(11) =95a(12) =109a(13) =127a(14) =158a(15) =176a(16) =197a(17) =203a(18) =205a(19) =206a(20) =208a(21) =209a(22) =211a(23) =218a(24) =232a(25) =239a(26) =256a(27) =274a(28) =305a(29) =323