a(n) = t(1+5n) where t = A001285 (Thue-Morse sequence).

Terms

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