A163367 - OEIS

A163367

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

1, 1, 2, 1, 2, 2, 2, 2, 1, 2, 2, 2, 2, 4, 4, 1, 2, 2, 2, 4, 2, 6, 4, 4, 1, 4, 4, 4, 4, 4, 2, 2, 4, 4, 4, 2, 2, 4, 4, 4, 4, 4, 2, 4, 4, 4, 4, 2, 2, 2, 4, 2, 4, 8, 4, 8, 4, 4, 4, 8, 2, 4, 4, 1, 4, 8, 2, 4, 4, 8, 4, 4, 2, 4, 2, 4, 4, 8, 4, 4, 2, 4, 4, 4, 4, 4

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OFFSET

1,3

LINKS

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

FORMULA

a(n) = A000010(A000005(A000203(n))) = A000010(A062068(n)) = A163109(A000203(n)).

MAPLE

with(numtheory): A163367:=n->phi(tau(sigma(n))): seq(A163367(n), n=1..150); # Wesley Ivan Hurt, Dec 19 2016

MATHEMATICA

Table[EulerPhi[DivisorSigma[0, DivisorSigma[1, n]]], {n, 100}] (* G. C. Greubel, Dec 19 2016 *)

PROG