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 A286950 #19 Jan 06 2018 18:46:31
%S A286950 1,1,-1,1,0,-1,1,-1,0,0,1,-1,1,0,0,1,-1,-1,-2,0,1,1,-1,-1,3,3,0,0,1,
%T A286950 -1,-1,0,-3,-4,0,1,1,-1,-1,0,4,-2,5,0,0,1,-1,-1,0,0,-3,9,-7,0,0,1,-1,
%U A286950 -1,0,0,6,-4,-8,10,0,0,1,-1,-1,0,0,1,-5,1,-6,-13,0,0,1
%N A286950 Square array A(n,k), n>=0, k>=0, read by antidiagonals, where column k is the expansion of Product_{j>=1} (1 - x^j)/(1 - x^(k*j))^k.
%H A286950 Seiichi Manyama, <a href="/A286950/b286950.txt">Antidiagonals n = 0..139, flattened</a>
%F A286950 G.f. of column k: Product_{j>=1} (1 - x^j)/(1 - x^(k*j))^k.
%e A286950 Square array begins:
%e A286950 1, 1, 1, 1, 1, ...
%e A286950 -1, 0, -1, -1, -1, ...
%e A286950 -1, 0, 1, -1, -1, ...
%e A286950 0, 0, -2, 3, 0, ...
%e A286950 0, 0, 3, -3, 4, ...
%Y A286950 Columns k=0-4 give: A010815, A000007, A106507, A286952, A286953.
%Y A286950 Diagonal gives A286956.
%Y A286950 Cf. A175595.
%K A286950 sign,tabl
%O A286950 0,19
%A A286950 _Seiichi Manyama_, May 17 2017