A353555 a(n) = 1 if n is an even number with an even number of prime factors (counted with multiplicity), otherwise 0.

0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for characteristic functions

Formula

a(n) = A059841(n) * A065043(n).

a(n) = A059841(n) - A353556(n).

a(n) = A065043(n) - A353557(n).

a(n) >= A353478(n).

Mathematica

A353555[n_] := Boole[EvenQ[n] && EvenQ[PrimeOmega[n]]];
Array[A353555, 100] (* Paolo Xausa, Jan 21 2026 *)

Prog

(PARI) A353555(n) = ((!(n%2))&&(!(bigomega(n)%2)));

Crossrefs

Characteristic function of A063745.

Cf. A059841, A065043, A353478, A353556, A353557, A353558.

Sequence in context: A038189 A072783 A353478 * A353476 A288377 A341609

Adjacent sequences: A353552 A353553 A353554 * A353556 A353557 A353558

Keyword

nonn

Author

Antti Karttunen, May 01 2022

Status

approved