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A049100
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Euler phi function applied 4 times.
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2
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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 1, 2, 1, 2, 2, 4, 1, 2, 2, 2, 2, 4, 2, 2, 2, 4, 2, 4, 1, 4, 2, 2, 2, 4, 2, 4, 2, 2, 4, 4, 2, 4, 4, 4, 2, 4, 2, 4, 2, 4, 2, 4, 2, 4, 4, 2, 4, 8, 2, 8, 2, 4, 4, 8, 2, 4, 4, 4, 4, 4, 4, 8, 2, 4, 4, 8, 4, 8, 4, 4
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,17
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FORMULA
| a(n) = phi(phi(phi(phi(n)))) = A000010(A000010(A000010(A000010(n)))) = A010554(A010554(n)) = A049099(A000010(n)).
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EXAMPLE
| n=163, the successive iterates applying Euler totient function are as follows: 163,162,54,18,6,2,1. The 5th term is 6, when Phi was applied 4 times. So a(163)=6
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MAPLE
| with(numtheory): seq(phi(phi(phi(phi(n)))), n=1..130); - Emeric Deutsch (deutsch(AT)duke.poly.edu), May 14 2006
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MATHEMATICA
| a(n)=Nest[ EulerPhi, n, 4 ]
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CROSSREFS
| Cf. A000010, A010554, A049099.
Sequence in context: A088323 A003652 A071625 * A030612 A120698 A184170
Adjacent sequences: A049097 A049098 A049099 * A049101 A049102 A049103
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu)
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EXTENSIONS
| Edited by N. J. A. Sloane (njas(AT)research.att.com) at the suggestion of Andrew Plewe, Jun 23 2007
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