%I #22 Feb 12 2021 05:33:24
%S 1,2,3,6,7,8,10,17,18,24,26,42,50,52,54,56,65,75,80,81,87,90,110,111,
%T 114,120,126,154,164,186,216,234,244,245,306,308,338,344,350,351,371,
%U 372,374,416,436,456,490,528,560,570,598,626,682,689,759,777,836,866
%N Numbers k such that phi(k) | sigma(k+4).
%H Ivan Neretin, <a href="/A015841/b015841.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[3000],Divisible[DivisorSigma[1, 4 + #], EulerPhi[#]] &] (* _David Nacin_, Mar 03 2012 *)
%o (PARI) isok(n) = !(sigma(n+4) % eulerphi(n)); \\ _Michel Marcus_, Feb 05 2017
%K nonn
%O 1,2
%A _Robert G. Wilson v_
%E a(1) = 1 inserted by _Ivan Neretin_, Feb 05 2017
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