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A163378 a(n) = sigma(phi(tau(n))). 3

%I

%S 1,1,1,3,1,3,1,3,3,3,1,3,1,3,3,7,1,3,1,3,3,3,1,7,3,3,3,3,1,7,1,3,3,3,

%T 3,12,1,3,3,7,1,7,1,3,3,3,1,7,3,3,3,3,1,7,3,7,3,3,1,7,1,3,3,12,3,7,1,

%U 3,3,7,1,7,1,3,3,3,3,7,1,7,7,3,1,7,3,3

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

%H G. C. Greubel, <a href="/A163378/b163378.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A000203(A000010(A000005(n))) = A000203(A163109(n)) = A062402(A000005(n)).

%t Table[DivisorSigma[1,EulerPhi[DivisorSigma[0,n]]],{n,100}] (* _Harvey P. Dale_, Jun 21 2016 *)

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

%Y Cf. A000005, A000010, A000203, A062402, A163109.

%K nonn

%O 1,4

%A _Jaroslav Krizek_, Jul 25 2009

%E More terms from _Harvey P. Dale_, Jun 21 2016

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Last modified September 18 14:45 EDT 2020. Contains 337169 sequences. (Running on oeis4.)