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 A364205 #13 Jul 29 2023 10:34:52
%S A364205 0,1,0,-1,1,1,0,0,0,0,1,-1,0,2,1,-2,1,1,0,-1,0,0,1,0,1,2,0,-2,1,0,0,
%T A364205 -1,1,0,2,-1,0,2,0,-2,1,2,0,-1,1,0,1,-2,0,1,1,-2,1,1,2,0,0,0,1,-1,0,2,
%U A364205 0,-3,2,0,0,-1,1,0,1,0,0,2,1,-2,2,2,0,-3,0,0,1,-2,2,2,1,-2,1,0,0,-1
%N A364205 Expansion of Sum_{k>=0} x^(3*k+2) / (1 + x^(3*k+2)).
%H A364205 Seiichi Manyama, <a href="/A364205/b364205.txt">Table of n, a(n) for n = 1..10000</a>
%F A364205 a(n) = Sum_{d|n, n/d==2 (mod 3)} (-1)^(d+1).
%t A364205 nmax = 92; CoefficientList[Series[Sum[x^(3 k + 2)/(1 + x^(3 k + 2)), {k, 0, nmax}], {x, 0, nmax}], x] // Rest
%t A364205 Table[DivisorSum[n, (-1)^(# + 1) &, MemberQ[{2}, Mod[n/#, 3]] &], {n, 1, 92}]
%Y A364205 Cf. A001822, A048272, A364014, A364204, A364235.
%K A364205 sign
%O A364205 1,14
%A A364205 _Ilya Gutkovskiy_, Jul 14 2023