A105825 - OEIS

%I #13 Nov 07 2017 18:31:24

%S 1,3,4,2,1,2,3,0,3,3,2,3,4,4,4,1,3,4,0,2,2,1,4,0,1,2,0,1,0,2,2,3,3,4,

%T 3,1,3,0,1,0,2,1,4,4,3,2,3,4,2,3,2,3,4,0,2,0,0,0,0,3,2,1,4,2,4,4,3,1,

%U 1,4,2,0,4,4,4,0,1,3,0,1,1,1,4,4,3,2,0,0,0,4,2,3,3,4,0,2,3,1,1,2,2,1,4,0,2

%N a(n) = sigma(n) (mod 5).

%H Antti Karttunen, <a href="/A105825/b105825.txt">Table of n, a(n) for n = 1..16384</a>

%H <a href="/index/Su#sums_of_divisors">Index entries for sequences related to sums of divisors</a>

%p A105825:= n-> (numtheory[sigma](n) mod 5):

%p seq (A105825(n), n=1..105); # _Jani Melik_, Jan 26 2011

%t Mod[DivisorSigma[1,Range[110]],5] (* _Harvey P. Dale_, Oct 03 2013 *)

%o (PARI) a(n)=sigma(n)%5

%Y Cf. A000203.

%Y 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).

%K easy,nonn

%O 1,2

%A _Shyam Sunder Gupta_, May 05 2005