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%I #18 Sep 08 2022 08:45:46
%S 1,3,3,12,3,7,7,15,28,12,7,28,12,15,15,72,12,60,15,28,31,28,15,31,72,
%T 28,31,60,15,60,31,91,31,39,31,195,39,31,60,60,28,63,42,60,60,60,31,
%U 168,91,168,60,96,39,63,60,63,63,60,31,124,72,63,124,312,60,124
%N a(n) = sigma(phi(sigma(n))).
%H G. C. Greubel, <a href="/A163372/b163372.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) = A000203(A000010(A000203(n))) = A000203(A062401(n)) = A062402(A000203(n)).
%p with(numtheory): A163372:=n->sigma(phi(sigma(n))): seq(A163372(n), n=1..100); # _Wesley Ivan Hurt_, Oct 06 2017
%t DivisorSigma[1, EulerPhi[DivisorSigma[1, Range[100]]]] (* _G. C. Greubel_, Dec 20 2016 *)
%o (PARI) vector(80, n, sigma(eulerphi(sigma(n)))) \\ _Michel Marcus_, Jul 31 2015
%o (Magma) [SumOfDivisors(EulerPhi(SumOfDivisors(n))): n in [1..80]]; // _Vincenzo Librandi_, Dec 20 2016
%Y Cf. A000010, A000203, A062401, A062402.
%K nonn
%O 1,2
%A _Jaroslav Krizek_, Jul 25 2009
%E More terms from _Michel Marcus_, Jul 31 2015