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Numbers k such that phi(k + 5) | sigma(k) + 5.
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%I #19 Sep 08 2019 18:15:52

%S 1,4,9,16,18,64,81,729,4096,59049,125316,262144,16777216

%N Numbers k such that phi(k + 5) | sigma(k) + 5.

%C a(14) > 10^12. - _Donovan Johnson_, Feb 28 2012

%t Select[Range[100000],

%t Divisible[DivisorSigma[1, #] + 5, EulerPhi[# + 5]] &] (* _David Nacin_, Feb 28 2012 *)

%K nonn

%O 1,2

%A _Robert G. Wilson v_

%E Offset corrected and a(11)-a(13) from _Donovan Johnson_, Feb 28 2012