Numbers whose base-7 representation has the same nonzero number of 4's and 5's.

Terms

a(0) =33a(1) =39a(2) =82a(3) =88a(4) =131a(5) =137a(6) =180a(7) =186a(8) =201a(9) =208a(10) =215a(11) =222a(12) =231a(13) =232a(14) =233a(15) =234a(16) =237a(17) =243a(18) =249a(19) =256a(20) =263a(21) =270a(22) =273a(23) =274a(24) =275a(25) =276a(26) =279a(27) =291a(28) =327a(29) =333