Each of the numbers describes the previous number, and is described by the next number.

Terms

a(0) =1a(1) =11a(2) =12a(3) =1121a(4) =1321a(5) =123121a(6) =132231a(7) =123222a(8) =112431a(9) =13214131a(10) =14322141a(11) =13423122a(12) =12324123a(13) =12233241a(14) =12233241a(15) =12233241a(16) =12233241a(17) =12233241a(18) =12233241a(19) =12233241a(20) =12233241a(21) =12233241a(22) =12233241a(23) =12233241a(24) =12233241a(25) =12233241a(26) =12233241a(27) =12233241a(28) =12233241a(29) =12233241