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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 STATUS approved

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Last modified January 22 13:41 EST 2020. Contains 331149 sequences. (Running on oeis4.)