A163370 a(n) = phi(sigma(phi(n))).

1, 1, 2, 2, 6, 2, 4, 6, 4, 6, 6, 6, 12, 4, 8, 8, 30, 4, 24, 8, 12, 6, 12, 8, 12, 12, 24, 12, 24, 8, 24, 30, 12, 30, 16, 12, 72, 24, 16, 30, 24, 12, 32, 12, 16, 12, 24, 30, 32, 12, 36, 16, 42, 24, 24, 16, 72, 24, 24, 30, 48, 24, 72, 36, 60, 12, 48, 36, 24, 16

Offset: 1

Author

Jaroslav Krizek, Jul 25 2009

Keywords

• nonn
• easy

Comments

a(n) = A000010(A000203(A000010(n))) = A000010(A062402(n)) = A062401(A000010(n)).

Links

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

Crossrefs

Cf. A000010, A000203, A062401, A062402.

Programs

Magma

[EulerPhi(SumOfDivisors(EulerPhi(n))): n in [1..80]]; // Vincenzo Librandi, Dec 21 2016

Maple

with(numtheory): A163370:=n->phi(sigma(phi(n))): seq(A163370(n), n=1..100); # Wesley Ivan Hurt, Dec 19 2016

Mathematica

EulerPhi[DivisorSigma[1,EulerPhi[Range[80]]]] (* Harvey P. Dale, Dec 24 2012 *)

PARI

vector(50, n, eulerphi(sigma(eulerphi(n)))) \\ G. C. Greubel, Dec 19 2016

Extensions

More terms from Harvey P. Dale, Dec 24 2012