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A066711 RATS: Reverse Add Then Sort the digits applied to previous term, starting with 9. 10
9, 18, 99, 189, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117, 288, 117 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(1) = A114612(1) = 9; A114611(3) = 2. [Reinhard Zumkeller, Mar 14 2012]

LINKS

Table of n, a(n) for n=1..49.

R. K. Guy, Conway's RATS and other reversals, Amer. Math. Monthly, 96 (1989), 425-428.

J. Thiel, Conway’s RATS Sequences in Base 3, Journal of Integer Sequences, 15 (2012), #12.9.2. - N. J. A. Sloane, Jan 02 2013

Eric Weisstein's World of Mathematics, RATS Sequence

Index entries for linear recurrences with constant coefficients, signature (0, 1).

FORMULA

Let a(n) = k, form m by Reversing the digits of k, Add m to k Then Sort the digits of the sum into increasing order to get a(n+1).

Periodic with period 2.

a(n+1) = A036839(a(n)). [Reinhard Zumkeller, Mar 14 2012]

EXAMPLE

668 -> 668 + 866 = 1534 -> 1345.

MATHEMATICA

NestList[ FromDigits[ Sort[ IntegerDigits[# + FromDigits[ Reverse[ IntegerDigits[#]]]]]] &, 9, 48] (* Jayanta Basu, Aug 13 2013 *)

Join[{9, 18, 99, 189}, LinearRecurrence[{0, 1}, {117, 288}, 45]] (* Ray Chandler, Aug 25 2015 *)

PROG

(Haskell)

a066711_list = iterate a036839 9  -- Reinhard Zumkeller, Mar 14 2012

CROSSREFS

Cf. A004000, A036839, A066710.

Cf. A004000, A066710, A209878, A209879, A209880.

Sequence in context: A186951 A176201 A186443 * A033651 A050250 A080453

Adjacent sequences:  A066708 A066709 A066710 * A066712 A066713 A066714

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Jan 19 2002

STATUS

approved

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Last modified July 17 16:38 EDT 2019. Contains 325107 sequences. (Running on oeis4.)