Add 2, then reverse digits!.

Terms

a(0) =0a(1) =2a(2) =4a(3) =6a(4) =8a(5) =1a(6) =3a(7) =5a(8) =7a(9) =9a(10) =11a(11) =31a(12) =33a(13) =53a(14) =55a(15) =75a(16) =77a(17) =97a(18) =99a(19) =101a(20) =301a(21) =303a(22) =503a(23) =505a(24) =705a(25) =707a(26) =907a(27) =909a(28) =119a(29) =121