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

20169, 111267, 337788, 1122255, 4446666, 1111113, 2222244, 4446666, 1111113, 2222244, 4446666, 1111113, 2222244, 4446666, 1111113, 2222244, 4446666, 1111113, 2222244, 4446666, 1111113, 2222244, 4446666, 1111113, 2222244, 4446666, 1111113, 2222244, 4446666

Offset: 1

Author

Reinhard Zumkeller, Mar 14 2012

Keywords

• nonn
• base

Comments

A114613(1) = 20169 is the smallest starting number for a RATS trajectory leading to a cycle of length 3: A114611(20169) = 3;

a(n + 3) = a(n) for n > 4.

Links

• Eric Weisstein's World of Mathematics, RATS Sequence
• Index entries for linear recurrences with constant coefficients, signature (0, 0, 1).

Crossrefs

Cf. A004000, A066710, A066711, A209879, A209880.

Programs

Haskell

a209878 n = a209878_list !! (n-1)
a209878_list = iterate a036839 20169

Mathematica

Join[{20169, 111267, 337788, 1122255},LinearRecurrence[{0, 0, 1},{4446666, 1111113, 2222244},25]] (* Ray Chandler, Aug 25 2015 *)

Formula

a(n + 1) = A036839(a(n)).