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Euler phi function applied 4 times.

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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; listen)

	OFFSET	`1,17`
	FORMULA	`a(n) = phi(phi(phi(phi(n)))) = A000010(A000010(A000010(A000010(n)))) = A010554(A010554(n)) = A049099(A000010(n)).`
	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`
	MAPLE	`with(numtheory): seq(phi(phi(phi(phi(n)))), n=1..130); - Emeric Deutsch (deutsch(AT)duke.poly.edu), May 14 2006`
	MATHEMATICA	`a(n)=Nest[ EulerPhi, n, 4 ]`
	CROSSREFS	`Cf. A000010, A010554, A049099.` `Adjacent sequences: A049097 A049098 A049099 this_sequence A049101 A049102 A049103` `Sequence in context: A088323 A003652 A071625 this_sequence A030612 A120698 A025919`
	KEYWORD	`nonn`
	AUTHOR	`Labos E. (labos(AT)ana.sote.hu)`
	EXTENSIONS	`Edited by njas at the suggestion of Andrew Plewe, Jun 23 2007`

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Last modified October 6 16:13 EDT 2008. Contains 144667 sequences.

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