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%I #9 Mar 12 2021 23:10:09
%S 2,3,5,7,9,11,13,15,17,19,23,25,29,31,35,37,41,43,47,49,53,59,61,67,
%T 71,73,79,83,89,95,97,101,103,107,109,113,119,121,127,131,137,139,143,
%U 149,151,157,163,167,169,173,179,181,191,193,197,199,209,211,223,227,229,233,239,241,251,257,263,269,271,277,281
%N Numbers k such that Euler totient phi(k) is a multiple of the arithmetic derivative of k.
%C Numbers k for which A000010(k) is a multiple of A003415(k), or equally, k for which A173557(k) is a multiple of A342001(k).
%t Select[Range[2, 281], Mod[EulerPhi[#], If[# < 2, 0, # Total[#2/#1 & @@@ FactorInteger[#]] ] &@ Abs[#]] == 0 &] (* _Michael De Vlieger_, Mar 12 2021 *)
%o (PARI)
%o A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
%o isA342008(n) = ((n>1)&&!(eulerphi(n)%A003415(n)));
%o for(n=2,2^8,if(isA342008(n),print1(n,", ")));
%Y Cf. A000010, A003415, A173557, A342001, A342009.
%Y Subsequences: A000040, A166374, A342418 (composite terms).
%Y Positions of ones in A342414.
%K nonn
%O 1,1
%A _Antti Karttunen_, Mar 12 2021
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