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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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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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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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KEYWORD
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nonn,base
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AUTHOR
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STATUS
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approved
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