Write 2n-1 in base 7 and juxtapose.

Terms

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