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A354036
a(n) = 1 if n is odd and sigma(n^2) == 1 (mod 4), otherwise 0.
3
1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1
OFFSET
1
FORMULA
a(n) = A000035(n) * [A010873(A065764(n)) == 1], where [ ] is the Iverson bracket.
a(n) = A000035(n) - A354035(n).
MATHEMATICA
a[n_] := If[OddQ[n] && Mod[DivisorSigma[1, n^2], 4] == 1, 1, 0]; Array[a, 100] (* Amiram Eldar, May 16 2022 *)
PROG
(PARI) A354036(n) = ((n%2)&&1==(sigma(n*n)%4));
CROSSREFS
Characteristic function of A354039.
Sequence in context: A285142 A267525 A014429 * A284948 A011637 A016229
KEYWORD
nonn
AUTHOR
Antti Karttunen, May 16 2022
STATUS
approved