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 A321436 #12 Apr 21 2024 11:39:06
%S A321436 1,0,-1,0,0,-1,0,1,-1,0,0,0,1,0,0,1,0,-2,1,1,-2,1,2,0,-1,0,-1,0,2,-2,
%T A321436 1,1,-4,0,3,-1,-1,3,-2,-1,0,-4,5,2,-3,2,3,-5,-3,6,-3,-1,0,-2,1,1,0,2,
%U A321436 7,-7,0,7,-9,-2,4,-3,2,6,-9,2,12,-12,1,9,-11,-3,7,0,-1,5
%N A321436 Expansion of Product_{1 <= i <= j} (1 - x^(i^2 + j^2)).
%H A321436 Robert Israel, <a href="/A321436/b321436.txt">Table of n, a(n) for n = 0..10000</a>
%F A321436 G.f.: Product_{k>0} (1 - x^k)^A025426(k).
%p A321436 N:= 100: # for a(1)..a(N)
%p A321436 P:= 1:
%p A321436 for i from 1 to floor(sqrt(N)) do
%p A321436 for j from i while i^2 + j^2 <= N do
%p A321436 P:= P * (1 - x^(i^2 + j^2))
%p A321436 od od:
%p A321436 S:= series(P,x,N+1):
%p A321436 seq(coeff(S,x,k),k=0..N): # _Robert Israel_, Apr 21 2024
%Y A321436 Cf. A025426, A321430, A321435, A321437.
%K A321436 sign,look
%O A321436 0,18
%A A321436 _Seiichi Manyama_, Nov 09 2018