Fixed under 1 -> 21, 2 -> 211.

Terms

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