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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 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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