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%I #18 Dec 08 2023 12:29:19
%S 1,9,81,225,2025,5625,50625,65025,585225,1625625,14630625
%N Numbers k such that sigma(phi(k^3)) = phi(sigma(k^3)).
%t Select[Range[3000000],DivisorSigma[1,EulerPhi[#^3]]==EulerPhi[ DivisorSigma[1,#^3]]&] (* _Harvey P. Dale_, Mar 23 2012 *)
%o (PARI) for(n=1,10^9, if(sigma(eulerphi(n^3))==eulerphi(sigma(n^3)),print(n)))
%Y Cf. A000010, A000203, A000578, A062401, A062402.
%K nonn,more
%O 1,2
%A _Jason Earls_, Aug 20 2001
%E a(11) from _Amiram Eldar_, Dec 08 2023
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