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A371970
Exponents k such that the binary expansion of 3^k has an even number of ones.
2
1, 2, 3, 5, 6, 8, 9, 12, 14, 17, 18, 21, 23, 24, 25, 26, 27, 31, 32, 33, 35, 37, 38, 39, 40, 42, 44, 45, 47, 51, 52, 55, 57, 58, 59, 60, 61, 64, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 81, 96, 99, 102, 104, 105, 106, 109, 112, 116, 127, 131, 132, 133, 134, 135, 136
OFFSET
1,2
LINKS
MAPLE
q:= n-> is(add(i, i=Bits[Split](3^n))::even):
select(q, [$0..150])[]; # Alois P. Heinz, Apr 24 2024
MATHEMATICA
Select[Range[136], EvenQ@ DigitCount[3^#, 2, 1] &] (* Michael De Vlieger, Apr 24 2024 *)
PROG
(PARI) is_a371970(k) = hammingweight(3^k)%2 == 0
CROSSREFS
Complement of A223024.
Sequence in context: A280744 A331072 A096276 * A239091 A272341 A075725
KEYWORD
nonn,base,easy
AUTHOR
Hugo Pfoertner, Apr 24 2024
STATUS
approved