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A049865 Number of iterations of unitary totient function (A047994) required to reach 1 from n. 4
0, 1, 2, 3, 4, 2, 3, 4, 5, 4, 5, 3, 4, 3, 5, 6, 7, 5, 6, 4, 4, 5, 6, 4, 5, 4, 5, 6, 7, 5, 6, 7, 5, 7, 5, 5, 6, 6, 5, 7, 8, 4, 5, 6, 8, 6, 7, 6, 7, 5, 8, 6, 7, 5, 8, 5, 6, 7, 8, 5, 6, 6, 7, 8, 7, 5, 6, 7, 7, 5, 6, 6, 7, 6, 7, 6, 6, 5, 6, 6, 7, 8, 9, 6, 9, 5, 6, 6, 7, 8, 7, 6, 6, 7, 7, 7, 8, 7, 7, 7, 8, 8, 9, 7, 7, 7, 8, 6, 7, 8, 7 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

a(A003271(n)) = n and a(m) <> n for m < A003271(n). [Reinhard Zumkeller, Aug 17 2011]

LINKS

T. D. Noe, Table of n, a(n) for n=1..10000

MAPLE

A049865 := proc(n)

    if n = 1 then

        0 ;

    else

        1+procname( A047994(n)) ;

    end if;

end proc: # R. J. Mathar, May 02 2013

MATHEMATICA

uphi[n_] := (f = FactorInteger[n]; Times @@ (f[[All, 1]]^f[[All, 2]] - 1)); uphi[n_ /; n <= 1] = 1; a[n_] := (k = 0; FixedPoint[ (k++; uphi[#]) & , n]; k-1); Table[a[n], {n, 1, 120}] (* Jean-Fran├žois Alcover, Jan 20 2012 *)

PROG

(Haskell)

a049865 n = length $ takeWhile (> 1) $ iterate a047994 n

a049865_list = map a049865 [1..]

-- Reinhard Zumkeller, Aug 17 2011

CROSSREFS

Sequence in context: A151925 A106653 A173524 * A070771 A274640 A245341

Adjacent sequences:  A049862 A049863 A049864 * A049866 A049867 A049868

KEYWORD

nonn,easy,nice

AUTHOR

David W. Wilson

STATUS

approved

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Last modified December 11 07:31 EST 2019. Contains 329914 sequences. (Running on oeis4.)