Numbers whose base-10 representation has the same number of 1's and 5's.

Terms

a(0) =0a(1) =2a(2) =3a(3) =4a(4) =6a(5) =7a(6) =8a(7) =9a(8) =15a(9) =20a(10) =22a(11) =23a(12) =24a(13) =26a(14) =27a(15) =28a(16) =29a(17) =30a(18) =32a(19) =33a(20) =34a(21) =36a(22) =37a(23) =38a(24) =39a(25) =40a(26) =42a(27) =43a(28) =44a(29) =46