

A181627


Number of iterations of phi(n) if n is a perfect totient number.


0



2, 3, 4, 4, 5, 5, 6, 7, 6, 8, 7, 8, 8, 7, 8, 10, 11, 11, 11, 11, 9, 10, 12, 10, 14, 13, 11, 16, 14, 12, 16, 17, 13, 14, 19, 15, 20, 16, 17, 18, 18, 19, 24, 19, 20, 21, 22, 29, 32, 28, 30, 22, 29, 23, 30, 32, 24, 25, 31, 35, 26, 34, 35, 27
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OFFSET

1,1


COMMENTS

Let phi^{i} denote the ith iteration of phi. a(n) is the smallest integer k such that phi^{k}(n) = 1 and Sum_{1<=i<=a(n)} phi^{i}(n) = n.


LINKS



FORMULA



MATHEMATICA

lst = (* get list from A082897 *); f[n_] := Length@ FixedPointList[ EulerPhi@ # &, n]  2; f@# & /@ lst (* Robert G. Wilson v, Nov 06 2010 *)


CROSSREFS



KEYWORD

nonn,more


AUTHOR



EXTENSIONS



STATUS

approved



