A361024 a(n) = 1 if n and sigma(n) have equal 2-adic valuations, otherwise 0, where sigma is the sum of divisors function.

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

Offset

1

Links

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

Index entries for characteristic functions

Index entries for sequences related to sigma(n)

Formula

a(n) = [A336937(n) = A007814(n)] = [A361025(n) = 0], where [ ] is the Iverson bracket.

a(n) = A361023(n) - A324903(n).

a(A003961(n)) = A010052(n).

Mathematica

a[n_] := If[OddQ[(Numerator[#]*Denominator[#]) &[DivisorSigma[-1, n]]], 1, 0]; Array[a, 100] (* Amiram Eldar, Mar 03 2023 *)

Prog

(PARI) A361024(n) = (valuation(sigma(n), 2)==valuation(n, 2));

Crossrefs

Characteristic function of A216780.

Cf. A000203, A003961, A007814, A010052, A319346, A324903, A336937, A361024, A361025.

Sequence in context: A369974 A369975 A369001 * A354037 A185118 A240332

Adjacent sequences: A361021 A361022 A361023 * A361025 A361026 A361027

Keyword

nonn

Author

Antti Karttunen, Mar 03 2023

Status

approved