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%I #30 Dec 13 2018 12:48:33
%S 3,6,7,11,15,19,21,23,27,31,33,42,43,51,57,59,62,69,70,71,77,79,83,84,
%T 87,93,103,131,139,141,159,163,165,177,187,189,191,199,211,213,223,
%U 235,237,251,267,270,271,282,285,287,297,311,315,316,321,330,331
%N Numbers k such that phi(k + 3) | sigma(k).
%H Vincenzo Librandi, <a href="/A015819/b015819.txt">Table of n, a(n) for n = 1..1000</a>
%p select(t -> (numtheory:-sigma(t)/numtheory:-phi(t+3))::integer, [$1..1000]); # _Robert Israel_, Dec 13 2018
%t Select[Range[1000], Divisible[DivisorSigma[1, #], EulerPhi[3 + #]] &] (* _David Nacin_, Mar 01 2012 *)
%o (PARI) is(n)=sigma(n)%(eulerphi(n+3))==0 \\ _Charles R Greathouse IV_, Sep 25 2012
%Y Cf. A056097.
%Y Contains A092109.
%K nonn
%O 1,1
%A _Robert G. Wilson v_
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