Ternary numbers consisting of a run of 2's, then a run of 1's, then a run of 0's.

Terms

a(0) =210a(1) =2100a(2) =2110a(3) =2210a(4) =21000a(5) =21100a(6) =21110a(7) =22100a(8) =22110a(9) =22210a(10) =210000a(11) =211000a(12) =211100a(13) =211110a(14) =221000a(15) =221100a(16) =221110a(17) =222100a(18) =222110a(19) =222210a(20) =2100000a(21) =2110000a(22) =2111000a(23) =2111100a(24) =2111110a(25) =2210000a(26) =2211000a(27) =2211100a(28) =2211110a(29) =2221000