A371970 Exponents k such that the binary expansion of 3^k has an even number of ones.

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

Hugo Pfoertner, Table of n, a(n) for n = 1..10000

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.

Cf. A000120, A000244, A001969, A011754, A078839.

Sequence in context: A280744 A331072 A096276 * A239091 A272341 A075725

Adjacent sequences: A371967 A371968 A371969 * A371971 A371972 A371973

Keyword

nonn,base,easy

Author

Hugo Pfoertner, Apr 24 2024

Status

approved