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 A074941 #21 Jun 06 2022 05:47:22 %S A074941 1,0,1,1,0,0,2,0,1,0,0,1,2,0,0,1,0,0,2,0,2,0,0,0,1,0,1,2,0,0,2,0,0,0, %T A074941 0,1,2,0,2,0,0,0,2,0,0,0,0,1,0,0,0,2,0,0,0,0,2,0,0,0,2,0,2,1,0,0,2,0, %U A074941 0,0,0,0,2,0,1,2,0,0,2,0,1,0,0,2,0,0,0,0,0,0,1,0,2,0,0,0,2,0,0,1,0,0,2,0,0 %N A074941 a(n) = sigma(n) mod 3. %H A074941 Antti Karttunen, <a href="/A074941/b074941.txt">Table of n, a(n) for n = 1..16384</a> %F A074941 a(n) = A010872(A000203(n)). - _Antti Karttunen_, Nov 05 2017 %p A074941 A074941:= n-> (numtheory[sigma](n) mod 3): %p A074941 seq (A074941(n), n=1..105); # _Jani Melik_, Jan 26 2011 %t A074941 a[n_] := Mod[DivisorSigma[1, n], 3]; Array[a, 100] (* _Amiram Eldar_, Jun 06 2022 *) %o A074941 (PARI) a(n)=sigma(n)%3 %Y A074941 Cf. A000203, A010872. %Y A074941 Differs from A002324 for the first time at n=49, where a(49) = 0, while A002324(49) = 3. %K A074941 easy,nonn %O A074941 1,7 %A A074941 _Benoit Cloitre_, Oct 04 2002