A063824 Numbers k such that sigma(phi(k^3)) = phi(sigma(k^3)).

1, 9, 81, 225, 2025, 5625, 50625, 65025, 585225, 1625625, 14630625

Offset

1,2

Links

Table of n, a(n) for n=1..11.

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

Cf. A000010, A000203, A000578, A062401, A062402.

Sequence in context: A207369 A208014 A208556 * A357450 A207560 A207415

Adjacent sequences: A063821 A063822 A063823 * A063825 A063826 A063827

Keyword

nonn,more

Author

Jason Earls, Aug 20 2001

Extensions

a(11) from Amiram Eldar, Dec 08 2023

Status

approved