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A105824
a(n) = sigma(n) mod 4.
11
1, 3, 0, 3, 2, 0, 0, 3, 1, 2, 0, 0, 2, 0, 0, 3, 2, 3, 0, 2, 0, 0, 0, 0, 3, 2, 0, 0, 2, 0, 0, 3, 0, 2, 0, 3, 2, 0, 0, 2, 2, 0, 0, 0, 2, 0, 0, 0, 1, 1, 0, 2, 2, 0, 0, 0, 0, 2, 0, 0, 2, 0, 0, 3, 0, 0, 0, 2, 0, 0, 0, 3, 2, 2, 0, 0, 0, 0, 0, 2, 1, 2, 0, 0, 0, 0, 0, 0, 2, 2, 0, 0, 0, 0, 0, 0, 2, 3, 0, 1, 2, 0, 0, 2, 0
OFFSET
1,2
FORMULA
a(n) = A010873(A000203(n)). - Antti Karttunen, Nov 07 2017
MAPLE
A105824:= n-> (numtheory[sigma](n) mod 4):
seq (A105824(n), n=1..105); # Jani Melik, Jan 26 2011
MATHEMATICA
Table[Mod[DivisorSigma[1, n], 4], {n, 100}] (* Wesley Ivan Hurt, Nov 07 2017 *)
PROG
(PARI) a(n)=sigma(n)%4
CROSSREFS
Sequences sigma(n) mod k: A053866 (k=2), A074941 (k=3), A105824 (k=4), A105825 (k=5), A084301 (k=6), A105826 (k=7), A105827 (k=8).
Sequence in context: A298082 A085919 A352613 * A171911 A180193 A229964
KEYWORD
easy,nonn
AUTHOR
Shyam Sunder Gupta, May 05 2005
STATUS
approved