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A081503
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Number of steps to reach a single digit when map in A081502 is iterated.
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1
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 2, 2, 2, 3, 3, 3, 2, 2, 2, 2, 3, 3, 3, 2, 2, 2, 2, 3, 3, 3, 2, 2, 2, 2, 3, 3, 3, 3, 2, 2, 2, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,18
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LINKS
| Matthew M. Conroy, Home page (listed instead of email address)
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FORMULA
| a(n) = O(log n).
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EXAMPLE
| 19 -> 3+9 = 12 -> 3+2 = 5, taking 2 steps, so a(19)=2.
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CROSSREFS
| Sequence in context: A176166 A167911 A037804 * A176508 A047971 A029432
Adjacent sequences: A081500 A081501 A081502 * A081504 A081505 A081506
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KEYWORD
| nonn,easy,base
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), Apr 22 2003
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EXTENSIONS
| More terms from Matthew Conroy (list1(AT)madandmoonly.com), Jan 16 2006
Formula from Charles R Greathouse IV (charles.greathouse(AT)case.edu), Aug 02 2010
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