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A105824 a(n) = sigma(n) mod 4. 6
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..16384

Index entries for sequences related to sums of divisors

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

Cf. A000203, A010873, A248150, A072461, A072462, A191217.

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: A166445 A298082 A085919 * A171911 A180193 A229964

Adjacent sequences:  A105821 A105822 A105823 * A105825 A105826 A105827

KEYWORD

easy,nonn

AUTHOR

Shyam Sunder Gupta, May 05 2005

STATUS

approved

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Last modified April 17 23:03 EDT 2021. Contains 343071 sequences. (Running on oeis4.)