Numbers with digits in {0,1,2} such that every other digit is strictly less than its neighbors.

Terms

a(0) =0a(1) =1a(2) =2a(3) =10a(4) =20a(5) =21a(6) =101a(7) =102a(8) =201a(9) =202a(10) =212a(11) =1010a(12) =1020a(13) =1021a(14) =2010a(15) =2020a(16) =2021a(17) =2120a(18) =2121a(19) =10101a(20) =10102a(21) =10201a(22) =10202a(23) =10212a(24) =20101a(25) =20102a(26) =20201a(27) =20202a(28) =20212a(29) =21201