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%I #23 Aug 31 2018 02:53:38
%S 5,7,15,21,23,35,47,71,77,87,132,155,191,263,295,297,310,357,359,428,
%T 431,437,479,503,527,595,638,660,719,759,790,837,839,863,983,1002,
%U 1105,1151,1155,1223,1269,1336,1376,1463,1495,1511,1512,1559,1615,1817,1871
%N Numbers k such that phi(k + 13) | sigma(k).
%H Vincenzo Librandi, <a href="/A015833/b015833.txt">Table of n, a(n) for n = 1..2000</a>
%t Select[Range[3000], Divisible[DivisorSigma[1, #], EulerPhi[13 + #]] &] (* _David Nacin_, Mar 03 2012 *)
%o (PARI) is(n)=sigma(n)%(eulerphi(n)+13)==0 \\ _Charles R Greathouse IV_, Sep 25 2012
%K nonn
%O 1,1
%A _Robert G. Wilson v_
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