A373157 - OEIS

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A373157

a(n) = 1 if the 2-adic valuation of n is a multiple of 3, otherwise 0.

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

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OFFSET

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..100000

Index entries for characteristic functions.

FORMULA

Multiplicative with a(p^e) = 1 if e is a multiple of 3, or p > 2, otherwise 0.

a(n) = [A007814(n) == 0 (mod 3)], where [ ] is the Iverson bracket.

a(n) = [A191255(n) = 0 or 3].

Sum_{k=1..n} a(k) ~ (4/7) * n. - Amiram Eldar, May 31 2024

MATHEMATICA

a[n_] := If[Divisible[IntegerExponent[n, 2], 3], 1, 0]; Array[a, 100] (* Amiram Eldar, May 31 2024 *)