a(n) = A047842(A047842(n)), say what you see, once repeated.

Terms

a(0) =1011a(1) =21a(2) =1112a(3) =1113a(4) =1114a(5) =1115a(6) =1116a(7) =1117a(8) =1118a(9) =1119a(10) =1031a(11) =1112a(12) =3112a(13) =3113a(14) =3114a(15) =3115a(16) =3116a(17) =3117a(18) =3118a(19) =3119a(20) =102112a(21) =3112a(22) =22a(23) =211213a(24) =211214a(25) =211215a(26) =211216a(27) =211217a(28) =211218a(29) =211219