A354037 - OEIS

A354037

a(n) = 1 if sigma(n)-n is a multiple of 4, otherwise 0.

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

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OFFSET

LINKS

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

Index entries for characteristic functions

Index entries for sequences related to sigma(n)

FORMULA

a(n) = 1 if A010873(A001065(n)) == 0, otherwise 0.

a(n) = [A010873(n) == A105824(n)], where [ ] is the Iverson bracket.

MATHEMATICA

a[n_] := If[Divisible[DivisorSigma[1, n] - n, 4], 1, 0]; Array[a, 100] (* Amiram Eldar, May 16 2022 *)

PROG