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A081503 Number of steps to reach a single digit when map in A081502 is iterated. 2
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; text; internal format)
OFFSET

0,18

LINKS

Table of n, a(n) for n=0..104.

FORMULA

a(n) = O(log n).

EXAMPLE

19 -> 3+9 = 12 -> 3+2 = 5, taking 2 steps, so a(19)=2.

MAPLE

A081503 := proc(n)

    local nitr, a ;

    nitr := n ;

    a := 0 ;

    while nitr > 9 do

        nitr := A081502(nitr) ;

        a := a+1 ;

    end do;

    a ;

end proc: # R. J. Mathar, Oct 03 2014

CROSSREFS

Sequence in context: A176166 A167911 A037804 * A176508 A241492 A227739

Adjacent sequences:  A081500 A081501 A081502 * A081504 A081505 A081506

KEYWORD

nonn,easy,base

AUTHOR

N. J. A. Sloane, Apr 22 2003

EXTENSIONS

More terms from Matthew Conroy, Jan 16 2006

Formula from Charles R Greathouse IV, Aug 02 2010

STATUS

approved

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Last modified September 26 05:09 EDT 2017. Contains 292502 sequences.