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A347883
a(n) = A342926(n) mod 3.
5
2, 2, 1, 0, 0, 1, 2, 0, 1, 2, 2, 2, 2, 0, 2, 0, 1, 1, 2, 0, 2, 2, 0, 2, 0, 0, 2, 1, 2, 0, 1, 1, 1, 2, 2, 2, 2, 0, 2, 2, 0, 2, 2, 2, 2, 2, 2, 2, 0, 2, 0, 1, 1, 1, 2, 2, 2, 2, 0, 2, 2, 0, 2, 0, 2, 0, 2, 1, 2, 2, 1, 2, 2, 0, 2, 1, 0, 2, 1, 0, 1, 2, 2, 1, 2, 0, 1, 2, 1, 0, 2, 0, 1, 2, 2, 0, 1, 1, 1, 1, 2, 0, 1, 2, 1
OFFSET
1,1
LINKS
FORMULA
a(n) = A342926(n) mod 3.
MATHEMATICA
ad[1] = 0; ad[n_] := n * Total@(Last[#]/First[#]& /@ FactorInteger[n]); a[n_] := Mod[ad[DivisorSigma[1, n]] - n, 3]; Array[a, 105] (* Amiram Eldar, Sep 18 2021 *)
PROG
(PARI)
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A342926(n) = (A003415(sigma(n))-n);
A347883(n) = (A342926(n)%3);
CROSSREFS
Cf. A000203, A003415, A342926, A347880 (positions of zeros).
Cf. also A347871.
Sequence in context: A370278 A369245 A353310 * A024712 A281497 A198243
KEYWORD
nonn
AUTHOR
Antti Karttunen, Sep 18 2021
STATUS
approved