A163371 a(n) = tau(phi(sigma(n))).

1, 2, 2, 4, 2, 3, 3, 4, 6, 4, 3, 6, 4, 4, 4, 8, 4, 8, 4, 6, 5, 6, 4, 5, 8, 6, 5, 8, 4, 8, 5, 9, 5, 6, 5, 12, 6, 5, 8, 8, 6, 6, 6, 8, 8, 8, 5, 12, 9, 12, 8, 8, 6, 6, 8, 6, 6, 8, 5, 10, 8, 6, 10, 12, 8, 10, 6, 9, 6, 10, 8, 12, 9, 9, 12, 10, 6, 10, 6, 12, 8, 9, 8, 12, 9, 8

Offset: 1

Author

Jaroslav Krizek, Jul 25 2009

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A000005, A000010, A000203, A062401, A062821.

Programs

Maple

with(numtheory): A163371:=n->tau(phi(sigma(n))): seq(A163371(n), n=1..150); # Wesley Ivan Hurt, Dec 19 2016

Mathematica

DivisorSigma[0, EulerPhi[DivisorSigma[1, Range[100]]]] (* G. C. Greubel, Dec 19 2016 *)

PARI

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

Formula

a(n) = A000005(A000010(A000203(n))) = A000005(A062401(n)) = A062821(A000203(n)).