A356876 Binary weight of the composite numbers (A002808).

1, 2, 1, 2, 2, 2, 3, 4, 1, 2, 2, 3, 3, 2, 3, 3, 4, 3, 4, 1, 2, 2, 3, 2, 3, 4, 2, 3, 3, 4, 4, 2, 3, 3, 4, 3, 4, 5, 3, 4, 4, 4, 5, 6, 1, 2, 2, 2, 3, 3, 2, 3, 4, 3, 4, 4, 2, 3, 3, 3, 4, 4, 5, 3, 4, 5, 4, 5, 5, 6, 2, 3, 4, 3, 4, 3, 4, 4, 4, 5, 6, 3, 4, 5, 4, 5, 5, 6, 4, 5, 5

Offset

1,2

Links

Karl-Heinz Hofmann, Table of n, a(n) for n = 1..10000

Formula

a(n) = A000120(A002808(n)).

Mathematica

DigitCount[#, 2, 1] & /@ Select[Range[125], CompositeQ] (* Amiram Eldar, Oct 03 2022 *)

Prog

(Python)
from sympy import isprime
print([bin(k)[2:].count("1") for k in range(4, 123) if not isprime(k)])
(PARI) forcomposite (k=0, 120, print1 (hammingweight(k), ", ")) \\ Hugo Pfoertner, Oct 03 2022

Crossrefs

Cf. A002808, A000120, A014499.

Sequence in context: A052954 A123505 A320779 * A114920 A283190 A030361

Adjacent sequences: A356873 A356874 A356875 * A356877 A356878 A356879

Keyword

base,nonn,easy

Author

Karl-Heinz Hofmann, Oct 02 2022

Status

approved