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A209880
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RATS: Reverse Add Then Sort the digits applied to previous term, starting with 29.
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7
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29, 112, 233, 556, 1112, 2233, 5555, 1111, 2222, 4444, 8888, 16777, 34589, 112333, 444455, 889999, 1788899, 1177777, 4558889, 13444447, 77888888, 156667777, 233444489, 1112278888, 11999, 11119, 1223, 4444, 8888, 16777, 34589, 112333, 444455, 889999, 1788899
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OFFSET
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1,1
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COMMENTS
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A114616(1) = 29 is the smallest starting number for a RATS trajectory leading to a cycle of length 18: A114611(29) = 18;
a(n + 18) = a(n) for n > 9.
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LINKS
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Table of n, a(n) for n=1..35.
Eric Weisstein's World of Mathematics, RATS Sequence
Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).
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FORMULA
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a(n + 1) = A036839(a(n)).
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MATHEMATICA
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NestList[FromDigits[Sort[IntegerDigits[#+IntegerReverse[#]]]]&, 29, 40] (* or *) PadRight[{29, 112, 233, 556, 1112, 2233, 5555, 1111, 2222}, 50, {4558889, 13444447, 77888888, 156667777, 233444489, 1112278888, 11999, 11119, 1223, 4444, 8888, 16777, 34589, 112333, 444455, 889999, 1788899, 1177777}] (* Harvey P. Dale, Sep 17 2018 *)
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PROG
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(Haskell)
a209880 n = a209880_list !! (n-1)
a209880_list = iterate a036839 29
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CROSSREFS
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Cf. A004000, A066710, A209878, A066711, A209879.
Sequence in context: A232787 A232852 A233117 * A232784 A232849 A233118
Adjacent sequences: A209877 A209878 A209879 * A209881 A209882 A209883
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KEYWORD
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nonn,base
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AUTHOR
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Reinhard Zumkeller, Mar 14 2012
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STATUS
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approved
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