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 A105826 #12 Jul 30 2021 19:12:31 %S A105826 1,3,4,0,6,5,1,1,6,4,5,0,0,3,3,3,4,4,6,0,4,1,3,4,3,0,5,0,2,2,4,0,6,5, %T A105826 6,0,3,4,0,6,0,5,2,0,1,2,6,5,1,2,2,0,5,1,2,1,3,6,4,0,6,5,6,1,0,4,5,0, %U A105826 5,4,2,6,4,2,5,0,5,0,3,4,2,0,0,0,3,6,1,5,6,3,0,0,2,4,1,0,0,3,2,0,4,6,6,0,3 %N A105826 a(n) = sigma(n) (mod 7). %H A105826 Antti Karttunen, <a href="/A105826/b105826.txt">Table of n, a(n) for n = 1..16384</a> %H A105826 <a href="/index/Su#sums_of_divisors">Index entries for sequences related to sums of divisors</a> %p A105826 A105826:= n-> (numtheory[sigma](n) mod 7): %p A105826 seq (A105826(n), n=1..105); # _Jani Melik_, Jan 26 2011 %t A105826 Mod[DivisorSigma[1,Range[110]],7] (* _Harvey P. Dale_, Jul 30 2021 *) %o A105826 (PARI) a(n)=sigma(n)%7 %Y A105826 Cf. A000203. %Y A105826 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 A105826 easy,nonn %O A105826 1,2 %A A105826 _Shyam Sunder Gupta_, May 05 2005