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A163376 a(n) = phi(tau(phi(n))). 1
1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 4, 2, 4, 4, 2, 6, 2, 4, 4, 4, 2, 4, 2, 4, 2, 2, 4, 4, 2, 2, 4, 2, 2, 4, 4, 6, 2, 2, 4, 4, 4, 6, 2, 4, 2, 4, 2, 2, 4, 4, 4, 4, 6, 4, 6, 4, 4, 4, 2, 4, 4, 2, 4, 6, 4, 4, 4, 4, 4 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

FORMULA

a(n) = A000010(A000005(A000010(n))) = A000010(A062821(n)) = A163109(A000010(n)).

MAPLE

with(numtheory): A163376:=n->phi(tau(phi(n))): seq(A163376(n), n=1..200); # Wesley Ivan Hurt, May 03 2017

MATHEMATICA

EulerPhi[DivisorSigma[0, EulerPhi[Range[100]]]] (* G. C. Greubel, Dec 20 2016 *)

PROG

(PARI) vector(100, n, eulerphi(numdiv(eulerphi(n)))) \\ G. C. Greubel, Dec 20 2016

CROSSREFS

Cf. A000005, A000010, A062821, A163109.

Sequence in context: A274828 A257474 A257317 * A261913 A088601 A261675

Adjacent sequences:  A163373 A163374 A163375 * A163377 A163378 A163379

KEYWORD

nonn,easy

AUTHOR

Jaroslav Krizek, Jul 25 2009

STATUS

approved

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Last modified September 30 11:32 EDT 2020. Contains 337439 sequences. (Running on oeis4.)