%I #20 Jan 08 2025 12:46:31
%S 1,2,3,6,19689,39378
%N Numbers k such that phi(k) | sigma_8(k).
%C sigma_8(n) is the sum of the 8th powers of the divisors of n.
%C sigma(16j+8,x)/phi(x) is an integer for j = 0, ..., 500 and 6 actual terms of this sequence. Compare to A015759, A015762, A015770 and A091285. - _Labos Elemer_, May 27 2004
%C No additional terms up to 5 million. - _Harvey P. Dale_, Jan 31 2016
%t Select[Range[40000],Divisible[DivisorSigma[8,#],EulerPhi[#]]&] (* _Harvey P. Dale_, Jan 31 2016 *)
%Y Cf. A015759, A015762, A015770, A091285.
%K nonn,more
%O 1,2
%A _Robert G. Wilson v_