A163379 a(n) = phi(phi(tau(n))).

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 2

Offset

1,16

Links

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

Formula

a(n) = A000010(A000010(A000005(n))) = A000010(A163109(n)) = A010554(A000005(n)).

Mathematica

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

Prog

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

Crossrefs

Cf. A000005, A000010, A010554, A163109.

Sequence in context: A328856 A053150 A295657 * A006466 A316439 A335078

Adjacent sequences: A163376 A163377 A163378 * A163380 A163381 A163382

Keyword

nonn

Author

Jaroslav Krizek, Jul 25 2009

Extensions

More terms added by G. C. Greubel, Dec 20 2016

Status

approved