a(n) = 10^n mod 7.

Terms

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