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A225320 The number of iterations of the bi-unitary totient A116550 needed to reach 1 starting with n. 2
0, 1, 2, 3, 4, 3, 4, 5, 6, 4, 5, 6, 7, 7, 7, 8, 9, 7, 8, 8, 8, 8, 9, 10, 11, 8, 9, 9, 10, 8, 9, 10, 10, 11, 12, 11, 12, 10, 10, 10, 11, 9, 10, 13, 12, 11, 12, 12, 13, 12, 13, 10, 11, 11, 10, 12, 10, 10, 11, 12, 13, 13, 14, 15, 13, 13, 14, 13, 14, 11, 12, 14, 15, 12, 13, 15, 14, 10, 11, 14 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..80.

FORMULA

The smallest x such that A116550^x(n)=1, where the operation Op^x denotes x nestings of the operator Op.

EXAMPLE

a(6)=3 because the first step is A116550(6) = 3, the second A116550(3)=2, the third A116550(2)=1, where 1 is reached.

MAPLE

A225320 := proc(n)

    option remember;

    if n = 1 then

        0;

    else

        1+procname(A116550(n)) ;

    end if;

end proc:

MATHEMATICA

A116550[1] = 1; A116550[n_] := With[{pp = Power @@@ FactorInteger[n]}, Count[Range[n], m_ /; Intersection[pp, Power @@@ FactorInteger[m]] == {}]]; a[n_] := a[n] = If[n == 1, 0, 1 + a[A116550[n]]]; Table[a[n], {n, 1, 80}] (* Jean-Fran├žois Alcover, Dec 16 2013 *)

CROSSREFS

Cf. A005424 (positions of records)

Sequence in context: A307531 A125619 A262519 * A308937 A123066 A330239

Adjacent sequences:  A225317 A225318 A225319 * A225321 A225322 A225323

KEYWORD

nonn

AUTHOR

R. J. Mathar, May 05 2013

STATUS

approved

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Last modified September 19 07:08 EDT 2021. Contains 347554 sequences. (Running on oeis4.)