This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A161590 #15 Dec 31 2022 10:45:46
%S A161590 1,3,9,29,69,2079,3999,6999,10677,20169,10049598,20008989,100014888,
%T A161590 100074268
%N A161590 Initial value x of a RATS trajectory x->A036839(x) ending in a cycle unreachable by any smaller initial value.
%C A161590 This is one way of book-keeping of new "destinies" (the smallest element of the cycle that the trajectory ends up in).
%C A161590 The value 1 is a placeholder for all non-cyclic trajectories.
%C A161590 Next terms are respectively <= 10000122228, 20000666679, 2000001113379, 2000001113559, 9999999999999, 100000044444447. See Branicky link for further upper bounds. - _Michael S. Branicky_, Dec 30 2022
%H A161590 Michael S. Branicky, <a href="/A161596/a161596_1.txt">RATS Sequence Cycles</a>.
%H A161590 Tanya Khovanova, <a href="http://blog.tanyakhovanova.com/?p=155">Destinies of Numbers</a>. [From _Tanya Khovanova_, Aug 10 2009]
%e A161590 The RATS (Reverse Add Then Sort) algorithm applied to 69 produces a sequence 69, 156, 78, 156, 78, ...
%e A161590 Its cycle {156, 78} appears not if the algorithm is started with any number in the range 0 to 68, so 69 is added to the sequence.
%Y A161590 Cf. A036839, A066710, A066711, A004000, A114611, A161592, A161593, A161596.
%K A161590 nonn,base,more
%O A161590 1,2
%A A161590 _J. H. Conway_ and _Tanya Khovanova_, Jun 14 2009, Jul 04 2009
%E A161590 10677, 20169 from _Wouter Meeussen_, Jul 04 2009
%E A161590 Definition rephrased by _R. J. Mathar_, Jul 08 2009
%E A161590 a(11)-a(14) from _Michael S. Branicky_, Dec 30 2022