Powers of 2 written in base 3.

Terms

a(0) =1a(1) =2a(2) =11a(3) =22a(4) =121a(5) =1012a(6) =2101a(7) =11202a(8) =100111a(9) =200222a(10) =1101221a(11) =2210212a(12) =12121201a(13) =102020102a(14) =211110211a(15) =1122221122a(16) =10022220021a(17) =20122210112a(18) =111022121001a(19) =222122012002