A353812 a(n) = 1 if sigma(n) is of the form 4m+2, otherwise 0.

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

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) = A347870(n) - A353811(n).

a(n) >= A353813(n).

Mathematica

a[n_] := If[Mod[DivisorSigma[1, n], 4] == 2, 1, 0]; Array[a, 100] (* Amiram Eldar, May 13 2022 *)

Prog

(PARI) A353812(n) = (2==(sigma(n)%4));

Crossrefs

Characteristic function of A191217.

Cf. A000203, A347870, A353811.

Differs from A353813 for the first time at n=325, where a(325) = 1, while A353813(325) = 0.

Sequence in context: A261990 A144601 A188009 * A353813 A353814 A144596

Adjacent sequences: A353809 A353810 A353811 * A353813 A353814 A353815

Keyword

nonn

Author

Antti Karttunen, May 13 2022

Status

approved