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%I #30 Feb 23 2018 18:54:03
%S 1,7,28,31,55,94,127,265,322,385,406,649,1504,1624,1990,2488,3115,
%T 3154,4402,5269,6265,6460,7258,7384,7579,8191,8455,8995,9229,9799,
%U 11815,12466,13114,13243,14146,15385,16309,16849,17731,20995,23359
%N Numbers n such that phi(n + 1) | sigma(n) for n congruent to 1 (mod 3).
%H Andrew Howroyd, <a href="/A015817/b015817.txt">Table of n, a(n) for n = 1..100</a>
%t Select[Range[1, 100000, 3], Divisible[DivisorSigma[1, #], EulerPhi[1 + #]] &] (* _David Nacin_, Mar 01 2012 *)
%o (PARI) is(n)=n%3==1 && sigma(n)%(eulerphi(n)+1)==0 \\ _Charles R Greathouse IV_, Sep 25 2012
%K nonn
%O 1,2
%A _Robert G. Wilson v_