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A360980 a(n) is the least multiple of n that is an odious number (A000069). 2
1, 2, 21, 4, 25, 42, 7, 8, 81, 50, 11, 84, 13, 14, 285, 16, 289, 162, 19, 100, 21, 22, 69, 168, 25, 26, 81, 28, 87, 570, 31, 32, 1089, 578, 35, 324, 37, 38, 117, 200, 41, 42, 301, 44, 405, 138, 47, 336, 49, 50, 357, 52, 265, 162, 55, 56, 171, 174, 59, 1140, 61 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
This sequence is well defined (see A178757).
LINKS
FORMULA
a(n) = A178757(n) * n.
a(n) = n iff n belongs to A000069.
MAPLE
f:= proc(n) local k;
for k from n by n do
if convert(convert(k, base, 2), `+`)::odd then return k fi
od
end proc:
map(f, [$1..100]); # Robert Israel, Mar 29 2023
MATHEMATICA
a[n_] := Module[{k = n}, While[EvenQ[DigitCount[k, 2, 1]], k +=n]; k]; Array[a, 100] (* Amiram Eldar, Aug 07 2023 *)
PROG
(PARI) a(n) = { forstep (m=n, oo, n, if (hammingweight(m)%2==1, return (m))) }
(Python)
def A360980(n):
k = n
while k.bit_count()&1^1:
k += n
return k # Chai Wah Wu, Feb 28 2023
CROSSREFS
Cf. A000069, A178757, A360981 (variant for evil numbers).
Sequence in context: A303218 A162536 A100980 * A122509 A024230 A358520
KEYWORD
nonn,base,look
AUTHOR
Rémy Sigrist, Feb 27 2023
STATUS
approved

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Last modified July 23 06:59 EDT 2024. Contains 374544 sequences. (Running on oeis4.)