The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 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-François 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

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