a(n) = n mod 4.

Terms

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