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A209878 RATS: Reverse Add Then Sort the digits applied to previous term, starting with 20169.

%I A209878 #12 Feb 16 2025 08:33:16
%S A209878 20169,111267,337788,1122255,4446666,1111113,2222244,4446666,1111113,
%T A209878 2222244,4446666,1111113,2222244,4446666,1111113,2222244,4446666,
%U A209878 1111113,2222244,4446666,1111113,2222244,4446666,1111113,2222244,4446666,1111113,2222244,4446666
%N A209878 RATS: Reverse Add Then Sort the digits applied to previous term, starting with 20169.
%C A209878 A114613(1) = 20169 is the smallest starting number for a RATS trajectory leading to a cycle of length 3: A114611(20169) = 3;
%C A209878 a(n + 3) = a(n) for n > 4.
%H A209878 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/RATSSequence.html">RATS Sequence</a>
%H A209878 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0, 0, 1).
%F A209878 a(n + 1) = A036839(a(n)).
%t A209878 Join[{20169, 111267, 337788, 1122255},LinearRecurrence[{0, 0, 1},{4446666, 1111113, 2222244},25]] (* _Ray Chandler_, Aug 25 2015 *)
%o A209878 (Haskell)
%o A209878 a209878 n = a209878_list !! (n-1)
%o A209878 a209878_list = iterate a036839 20169
%Y A209878 Cf. A004000, A066710, A066711, A209879, A209880.
%K A209878 nonn,base
%O A209878 1,1
%A A209878 _Reinhard Zumkeller_, Mar 14 2012