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Numbers k such that phi(k) divides sigma_0(k).
0

%I #10 May 15 2024 01:30:26

%S 1,2,3,6,8,10,18,24,30

%N Numbers k such that phi(k) divides sigma_0(k).

%t Select[Range[30], Divisible[DivisorSigma[0, #], EulerPhi[#]] &] (* _Amiram Eldar_, May 15 2024 *)

%Y Cf. A000005 (sigma_0), A000010 (phi).

%K nonn,fini,full

%O 1,2

%A _David W. Wilson_