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A086358
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Digital root of n!.
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3
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1, 1, 2, 6, 6, 3, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9
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OFFSET
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0,3
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COMMENTS
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a(n) = 9 for n >= 6.
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LINKS
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Table of n, a(n) for n=0..105.
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FORMULA
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a(n) = A010888(n!) = fixed-point of A007953(n!). It equals n! modulo(9); at r = 0 use 9.
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EXAMPLE
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n=5, 5!=120, iteration list={120,3},a(5)=3.
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MATHEMATICA
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sud[x_] := Apply[Plus, DeleteCases[IntegerDigits[x], 0]] Table[FixedPoint[sud, w! ], {w, 1, 128}]
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CROSSREFS
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Cf. A000142, A086353-A086361, A007953, A010888, A038194, A029898, A004152.
Sequence in context: A153845 A105815 A136696 * A004152 A071678 A316164
Adjacent sequences: A086355 A086356 A086357 * A086359 A086360 A086361
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KEYWORD
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nonn,base,easy
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AUTHOR
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Labos Elemer, Jul 21 2003
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EXTENSIONS
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a(0)=1 prepended by Alois P. Heinz, Dec 05 2018
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STATUS
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approved
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