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A049865 Number of iterations of unitary totient function (A047994) required to reach 1 from n. 7
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
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-François 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
KEYWORD
nonn,easy,nice
AUTHOR
STATUS
approved

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Last modified April 19 23:40 EDT 2024. Contains 371798 sequences. (Running on oeis4.)