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A049099 a(n) = Euler phi function applied thrice to n. 6
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 2, 4, 1, 2, 2, 2, 2, 4, 2, 4, 2, 2, 2, 4, 2, 4, 4, 4, 4, 4, 2, 4, 2, 4, 4, 8, 2, 4, 4, 4, 4, 10, 4, 4, 4, 8, 4, 8, 2, 8, 4, 4, 4, 12, 4, 8, 4, 4, 8, 8, 4, 8, 8, 8, 4, 8, 4, 8, 4, 8, 4, 8, 4, 8, 8, 6, 8, 16, 4, 16, 4, 8, 8, 16, 4, 8, 8, 8, 10, 8, 8, 16, 4, 8, 8, 16 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,11

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..10000

Paul Erdős, Andrew Granville, Carl Pomerance and Claudia Spiro, On the normal behavior of the iterates of some arithmetic functions, Analytic number theory, Birkhäuser Boston, 1990, pp. 165-204.

Paul Erdos, Andrew Granville, Carl Pomerance and Claudia Spiro, On the normal behavior of the iterates of some arithmetic functions, Analytic number theory, Birkhäuser Boston, 1990, pp. 165-204. [Annotated copy with A-numbers]

Boris Putievskiy, Transformations [Of] Integer Sequences And Pairing Functions, arXiv preprint arXiv:1212.2732, 2012.

FORMULA

a(n) = A000010(A010554(n)) = A000010(A000010(A000010(n))). - Antti Karttunen, Aug 22 2017

EXAMPLE

n=163: the successive iterates of Euler totient function are 163,162,54,18,6,2,1. The 4th term is 18, when Phi was applied 3 times. So a(163)=18.

MATHEMATICA

a(n)=Nest[ EulerPhi, n, 3 ]

PROG

(PARI) A049099(n) = eulerphi(eulerphi(eulerphi(n))); \\ Antti Karttunen, Aug 22 2017

CROSSREFS

Cf. A000010, A010554, A049100, A049107, A049115.

Sequence in context: A161283 A226516 A002300 * A181776 A243036 A230224

Adjacent sequences:  A049096 A049097 A049098 * A049100 A049101 A049102

KEYWORD

nonn

AUTHOR

Labos Elemer

STATUS

approved

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Last modified November 13 12:45 EST 2019. Contains 329094 sequences. (Running on oeis4.)