A163376 a(n) = phi(tau(phi(n))).

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

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: A364136 A257474 A257317 * A261913 A088601 A261675

Adjacent sequences: A163373 A163374 A163375 * A163377 A163378 A163379

Keyword

nonn,easy

Author

Jaroslav Krizek, Jul 25 2009

Status

approved