A353569 - OEIS

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A353569

a(n) = 1 if n is an odd number divisible by a square > 1, otherwise 0.

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

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OFFSET

LINKS

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

Index entries for characteristic functions.

FORMULA

a(n) = A000035(n) * A107078(n).

a(n) = A000035(n) - A323239(n).

a(n) <= A353626(n).

Asymptotic mean: Limit_{m->oo} (1/m) * Sum_{k=1..m} a(k) = 1/2 - 4/Pi^2 = 0.094715... . - Amiram Eldar, Jul 24 2022

MATHEMATICA

a[n_] := If[OddQ[n] && !SquareFreeQ[n], 1, 0]; Array[a, 100] (* Amiram Eldar, Jul 24 2022 *)