a(n) = (greatest base 7 digit of n) - (least base 7 digit of n).

Terms

a(0) =0a(1) =0a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =1a(8) =0a(9) =1a(10) =2a(11) =3a(12) =4a(13) =5a(14) =2a(15) =1a(16) =0a(17) =1a(18) =2a(19) =3a(20) =4a(21) =3a(22) =2a(23) =1a(24) =0a(25) =1a(26) =2a(27) =3a(28) =4a(29) =3