RATS: Reverse Add Then Sort the digits applied to previous term, starting with 1.

Terms

a(0) =1a(1) =2a(2) =4a(3) =8a(4) =16a(5) =77a(6) =145a(7) =668a(8) =1345a(9) =6677a(10) =13444a(11) =55778a(12) =133345a(13) =666677a(14) =1333444a(15) =5567777a(16) =12333445a(17) =66666677a(18) =133333444a(19) =556667777a(20) =1233334444a(21) =5566667777a(22) =12333334444a(23) =55666667777a(24) =123333334444a(25) =556666667777