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%I #25 Dec 04 2023 01:34:41
%S 0,1,2,6,4,12,6,28,24,32,10,64,12,60,72,120,16,126,18,176,132,140,22,
%T 288,120,192,234,336,28,336,30,496,300,320,312,660,36,396,408,800,40,
%U 648,42,800,792,572,46,1216,336,860,672,1104,52,1188,680
%N a(n) = phi(n) * (sigma(n) - n).
%H G. C. Greubel, <a href="/A007517/b007517.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A000010(n)*A001065(n). - _Michel Marcus_, Mar 22 2018
%F Sum_{k=1..n} a(k) ~ c * n^2 / 3, where c = A065465 - A059956 = 0.273586... . - _Amiram Eldar_, Dec 04 2023
%p with(numtheory): seq(phi(n)*(sigma(n)-n),n=1..60); # _Muniru A Asiru_, Mar 22 2018
%t Table[EulerPhi[n](DivisorSigma[1,n]-n),{n,60}] (* _Harvey P. Dale_, Mar 16 2013 *)
%o (GAP) List([1..60],n->Phi(n)*(Sigma(n)-n)); # _Muniru A Asiru_, Mar 22 2018
%o (PARI) for(n=1,50, print1(eulerphi(n)*(sigma(n) - n), ", ")) \\ _G. C. Greubel_, Mar 22 2018
%Y Cf. A000010, A000203, A001065, A059956, A065465.
%K nonn,easy
%O 1,3
%A _Walter Nissen_
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