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A384427 Evil numbers that are not a multiple of any other evil number.

%I A384427 #33 Jun 20 2025 10:46:56
%S A384427 3,5,17,23,29,43,53,71,77,83,89,101,113,139,149,163,169,197,209,257,
%T A384427 263,269,277,281,287,293,311,317,329,337,343,347,349,353,359,373,383,
%U A384427 389,401,407,413,427,449,461,467,469,479,503,509,523,533,547,553,571,593,599
%N A384427 Evil numbers that are not a multiple of any other evil number.
%H A384427 Robert Israel, <a href="/A384427/b384427.txt">Table of n, a(n) for n = 1..10000</a>
%p A384427 isevil:= proc(n) convert(convert(n,base,2),`+`)::even end proc:
%p A384427 N:= 1000: # for terms <= N
%p A384427 V:= Vector(N,1):
%p A384427 for i from 1 to N do
%p A384427     if isevil(i) then V[[seq(j,j=2*i .. N, i)]]:= 0
%p A384427     else V[i]:= 0
%p A384427     fi
%p A384427 od:
%p A384427 select(t -> V[t]=1, [$1..N]); # _Robert Israel_, Jun 18 2025
%t A384427 evilQ[n_] := EvenQ[DigitCount[n, 2, 1]]; q[n_] := evilQ[n] && AllTrue[Divisors[n], # == n || ! evilQ[#] &]; Select[Range[600], q] (* _Amiram Eldar_, May 31 2025 *)
%o A384427 (PARI) isevil(n) = hammingweight(n) % 2 == 0;
%o A384427 noevildiv(n) = {fordiv(n, d, if ((d < n) && isevil(d), return (0)); ); 1; }
%o A384427 isok(n) = isevil(n) && noevildiv(n); \\ _Michel Marcus_, May 31 2025
%Y A384427 Union of A217790 and A027699.
%Y A384427 Cf. A001969, A129771.
%K A384427 nonn,base
%O A384427 1,1
%A A384427 _Francisco J. Muñoz_, May 28 2025