This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A105825 #13 Nov 07 2017 18:31:24 %S A105825 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 A105825 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 A105825 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 A105825 a(n) = sigma(n) (mod 5). %H A105825 Antti Karttunen, <a href="/A105825/b105825.txt">Table of n, a(n) for n = 1..16384</a> %H A105825 <a href="/index/Su#sums_of_divisors">Index entries for sequences related to sums of divisors</a> %p A105825 A105825:= n-> (numtheory[sigma](n) mod 5): %p A105825 seq (A105825(n), n=1..105); # _Jani Melik_, Jan 26 2011 %t A105825 Mod[DivisorSigma[1,Range[110]],5] (* _Harvey P. Dale_, Oct 03 2013 *) %o A105825 (PARI) a(n)=sigma(n)%5 %Y A105825 Cf. A000203. %Y A105825 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 A105825 easy,nonn %O A105825 1,2 %A A105825 _Shyam Sunder Gupta_, May 05 2005