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a(n) = phi(tau(phi(n))).
1

%I #13 May 04 2017 00:19:39

%S 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,

%T 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,

%U 2,4,4,4,4,6,4,6,4,4,4,2,4,4,2,4,6,4,4,4,4,4

%N a(n) = phi(tau(phi(n))).

%H G. C. Greubel, <a href="/A163376/b163376.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A000010(A000005(A000010(n))) = A000010(A062821(n)) = A163109(A000010(n)).

%p with(numtheory): A163376:=n->phi(tau(phi(n))): seq(A163376(n), n=1..200); # _Wesley Ivan Hurt_, May 03 2017

%t EulerPhi[DivisorSigma[0, EulerPhi[Range[100]]]] (* _G. C. Greubel_, Dec 20 2016 *)

%o (PARI) vector(100, n, eulerphi(numdiv(eulerphi(n)))) \\ _G. C. Greubel_, Dec 20 2016

%Y Cf. A000005, A000010, A062821, A163109.

%K nonn,easy

%O 1,5

%A _Jaroslav Krizek_, Jul 25 2009