A379966 a(n) = 1 if n is an even squarefree number, otherwise 0.

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

Offset

1

Links

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

Index entries for characteristic functions.

Formula

a(n) = A008966(n) - A323239(n).

a(n) = A059841(n) * A008966(n).

a(n) = abs(A292273(n)).

Sum_{k=1..n} a(k) ~ 2*n/Pi^2. - Amiram Eldar, Jan 22 2025

Mathematica

a[n_] := Boole[EvenQ[n] && SquareFreeQ[n]]; Array[a, 100] (* Amiram Eldar, Jan 22 2025 *)

Prog

(PARI) A379966(n) = (!(n%2) && issquarefree(n));

Crossrefs

Characteristic function of A039956, even squarefree numbers.

Absolute values of A292273.

Cf. A008966, A059841, A185197, A323239.

Cf. also A379970.

Sequence in context: A324964 A285957 A292273 * A324772 A285949 A285530

Adjacent sequences: A379963 A379964 A379965 * A379967 A379968 A379969

Keyword

nonn,new

Author

Antti Karttunen, Jan 22 2025

Status

approved