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 A266649 #6 Jan 02 2016 07:56:34
%S A266649 1,0,0,-1,-1,-1,-2,-1,-2,-1,-1,1,-1,3,2,5,4,8,7,11,8,12,11,13,10,9,9,
%T A266649 7,3,-2,-5,-13,-16,-25,-28,-48,-44,-66,-60,-82,-82,-104,-95,-120,-103,
%U A266649 -131,-107,-133,-98,-124,-85,-94,-42,-51,9,7,83,100,181,208,298
%N A266649 Expansion of Product_{k>=1} 1 - x^(3*k)/(1-x^k).
%H A266649 Vaclav Kotesovec, <a href="/A266649/b266649.txt">Table of n, a(n) for n = 0..5000</a>
%F A266649 G.f.: Product_{k>=1} (1 - x^k - x^(3*k)) / (1 - x^k).
%t A266649 nmax = 100; CoefficientList[Series[Product[1-x^(3*k)/(1-x^k), {k, 1, nmax}], {x, 0, nmax}], x]
%Y A266649 Cf. A000726, A100405, A266647, A266648, A266650.
%K A266649 sign
%O A266649 0,7
%A A266649 _Vaclav Kotesovec_, Jan 02 2016