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 A300575 #8 Nov 22 2019 03:37:50
%S A300575 1,1,0,-1,-1,1,1,-1,-2,0,2,0,-3,-1,3,2,-3,-3,3,4,-3,-6,2,7,-1,-8,0,10,
%T A300575 2,-11,-4,12,7,-13,-10,13,13,-13,-17,13,22,-11,-26,9,31,-6,-36,2,41,3,
%U A300575 -46,-9,51,17,-55,-26,59,36,-62,-48,63,61,-64,-75,64,92,-60,-109,55,127,-48,-147,37,167
%N A300575 Coefficient of x^n in (1+x)(1-x^3)(1+x^5)(1-x^7)(1+x^9)...
%H A300575 Seiichi Manyama, <a href="/A300575/b300575.txt">Table of n, a(n) for n = 0..1000</a>
%F A300575 O.g.f.: Product_{n >= 0} (1 + (-1)^n x^(2n+1)).
%F A300575 a(n) = Sum (-1)^k where the sum is over all strict integer partitions of n into odd parts and k is the number of parts not congruent to 1 modulo 4.
%t A300575 CoefficientList[Series[QPochhammer[-x,-x^2],{x,0,100}],x]
%Y A300575 Cf. A000009, A010815, A027193, A067659, A078408, A081362, A220418, A290261, A292043, A292137, A300574.
%K A300575 sign,look
%O A300575 0,9
%A A300575 _Gus Wiseman_, Mar 09 2018