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%I #24 Sep 08 2022 08:44:40
%S 1,2,3,4,6,8,9,10,12,13,16,18,19,20,24,35,36,45,49,51,74,77,79,84,91,
%T 104,108,113,124,129,130,144,148,180,198,219,224,279,286,308,380,407,
%U 434,435,459,490,584,609,610,616,624,627,628,640,644,679,779
%N Numbers k such that phi(k) | sigma(k + 11).
%H Harvey P. Dale, <a href="/A015858/b015858.txt">Table of n, a(n) for n = 1..1000</a>
%t Select[Range[800],Divisible[DivisorSigma[1,#+11],EulerPhi[#]]&] (* _Harvey P. Dale_, Aug 01 2016 *)
%o (PARI) is(n)=!(sigma(n+11)%eulerphi(n)) \\ _Charles R Greathouse IV_, Sep 25 2012
%o (Magma) [n: n in [1..900] | DivisorSigma(1,n+11) mod EulerPhi(n) eq 0]; // _G. C. Greubel_, Dec 13 2018
%Y Cf. A015834 (m=1), A015837 (m=2), A015840 (m=3), A015841 (m=4), A015843 (m=5), A015844 (m=6), A015845 (m=7), A015851 (m=8), A015853 (m=9), A015856 (m=10), this sequence (m=11), A015859 (m=12), A015860 (m=13).
%K nonn
%O 1,2
%A _Robert G. Wilson v_
%E Missing a(1)=1 inserted by _Sean A. Irvine_, Dec 13 2018
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