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A360980 a(n) is the least multiple of n that is an odious number (A000069).

%I A360980 #22 Aug 07 2023 02:12:06
%S A360980 1,2,21,4,25,42,7,8,81,50,11,84,13,14,285,16,289,162,19,100,21,22,69,
%T A360980 168,25,26,81,28,87,570,31,32,1089,578,35,324,37,38,117,200,41,42,301,
%U A360980 44,405,138,47,336,49,50,357,52,265,162,55,56,171,174,59,1140,61
%N A360980 a(n) is the least multiple of n that is an odious number (A000069).
%C A360980 This sequence is well defined (see A178757).
%H A360980 Robert Israel, <a href="/A360980/b360980.txt">Table of n, a(n) for n = 1..10000</a>
%F A360980 a(n) = A178757(n) * n.
%F A360980 a(n) = n iff n belongs to A000069.
%p A360980 f:= proc(n) local k;
%p A360980   for k from n by n do
%p A360980     if convert(convert(k,base,2),`+`)::odd then return k fi
%p A360980   od
%p A360980 end proc:
%p A360980 map(f, [$1..100]); # _Robert Israel_, Mar 29 2023
%t A360980 a[n_] := Module[{k = n}, While[EvenQ[DigitCount[k, 2, 1]], k +=n]; k]; Array[a, 100] (* _Amiram Eldar_, Aug 07 2023 *)
%o A360980 (PARI) a(n) = { forstep (m=n, oo, n, if (hammingweight(m)%2==1, return (m))) }
%o A360980 (Python)
%o A360980 def A360980(n):
%o A360980     k = n
%o A360980     while k.bit_count()&1^1:
%o A360980         k += n
%o A360980     return k # _Chai Wah Wu_, Feb 28 2023
%Y A360980 Cf. A000069, A178757, A360981 (variant for evil numbers).
%K A360980 nonn,base,look
%O A360980 1,2
%A A360980 _Rémy Sigrist_, Feb 27 2023