Numbers in base 3.

Terms

a(0) =0a(1) =1a(2) =2a(3) =10a(4) =11a(5) =12a(6) =20a(7) =21a(8) =22a(9) =100a(10) =101a(11) =102a(12) =110a(13) =111a(14) =112a(15) =120a(16) =121a(17) =122a(18) =200a(19) =201a(20) =202a(21) =210a(22) =211a(23) =212a(24) =220a(25) =221a(26) =222a(27) =1000a(28) =1001a(29) =1002