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A063824
Numbers k such that sigma(phi(k^3)) = phi(sigma(k^3)).
0
1, 9, 81, 225, 2025, 5625, 50625, 65025, 585225, 1625625, 14630625
OFFSET
1,2
MATHEMATICA
Select[Range[3000000], DivisorSigma[1, EulerPhi[#^3]]==EulerPhi[ DivisorSigma[1, #^3]]&] (* Harvey P. Dale, Mar 23 2012 *)
PROG
(PARI) for(n=1, 10^9, if(sigma(eulerphi(n^3))==eulerphi(sigma(n^3)), print(n)))
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Jason Earls, Aug 20 2001
EXTENSIONS
a(11) from Amiram Eldar, Dec 08 2023
STATUS
approved