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%I #24 Jan 10 2019 10:23:04
%S 3,5,7,10,15,21,24,30,31,33,42,47,57,69,78,79,93,102,114,127,129,135,
%T 145,161,174,177,186,210,213,216,223,231,237,238,239,249,258,264,270,
%U 282,297,309,318,355,367,371,376,393,399,402,417,418,435,438,455,456
%N Numbers k such that phi(k + 9) | sigma(k).
%C Includes 6*A023204. Thus Dickson's conjecture implies the sequence is infinite. - _Robert Israel_, Jan 10 2019
%H Vincenzo Librandi, <a href="/A015827/b015827.txt">Table of n, a(n) for n = 1..3000</a>
%p filter:= n -> (numtheory:-sigma(n)/numtheory:-phi(n+9))::integer:
%p select(filter, [$1..1000]); # _Robert Israel_, Jan 10 2019
%t Select[Range[1000], Divisible[DivisorSigma[1, #], EulerPhi[9 + #]] &] (* _David Nacin_, Mar 01 2012 *)
%o (PARI) is(n)=sigma(n)%(eulerphi(n)+9)==0 \\ _Charles R Greathouse IV_, Sep 25 2012
%Y Cf. A015849, A023204.
%K nonn
%O 1,1
%A _Robert G. Wilson v_
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