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A039651 Number of iterations of f(x) = phi(x)+1 on n required to reach a prime. 12
1, 0, 0, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 2, 2, 0, 1, 0, 2, 1, 1, 0, 2, 2, 1, 1, 1, 0, 2, 0, 1, 2, 1, 3, 1, 0, 1, 3, 1, 0, 1, 0, 2, 3, 1, 0, 1, 1, 2, 3, 3, 0, 1, 1, 3, 1, 1, 0, 1, 0, 1, 1, 3, 2, 2, 0, 3, 4, 3, 0, 3, 0, 1, 1, 1, 1, 3, 0, 3, 2, 1, 0, 3, 3, 1, 2, 1, 0, 3, 1, 4, 1, 1, 1, 3, 0, 1, 1, 1, 0, 3, 0, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,15

LINKS

T. D. Noe, Table of n, a(n) for n = 1..1000

MATHEMATICA

Table[Length[NestWhileList[EulerPhi[#] + 1 &, n, UnsameQ, All]] - 2, {n, 100}] (* T. D. Noe, Oct 17 2013 *)

CROSSREFS

Cf. A039649, A039650, A039651, A039652, A039653, A039654, A039655, A039656.

Sequence in context: A113685 A049825 A287443 * A264403 A038190 A279947

Adjacent sequences:  A039648 A039649 A039650 * A039652 A039653 A039654

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified November 15 08:58 EST 2019. Contains 329144 sequences. (Running on oeis4.)