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 A303992 #29 Oct 14 2019 04:26:15
%S A303992 1,1,-3,3,-1,1,-3,0,8,-6,-6,8,0,-3,1,1,-3,0,5,3,-6,-13,9,15,0,-15,-9,
%T A303992 13,6,-3,-5,0,3,-1,1,-3,0,5,0,3,-13,-6,9,9,24,-21,-24,-9,3,44,3,-9,
%U A303992 -24,-21,24,9,9,-6,-13,3,0,5,0,-3,1
%N A303992 Triangular array T(n,k) giving coefficients in expansion of Product_{j=1..n} (1-x^j)^3.
%H A303992 Seiichi Manyama, <a href="/A303992/b303992.txt">Rows n = 0..26, flattened</a>
%e A303992 Irregular triangle starts:
%e A303992 n\k| 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
%e A303992 ---+-----------------------------------------------------------------------
%e A303992 0 | 1;
%e A303992 1 | 1, -3, 3, -1;
%e A303992 2 | 1, -3, 0, 8, -6, -6, 8, 0, -3, 1;
%e A303992 3 | 1, -3, 0, 5, 3, -6, -13, 9, 15, 0, -15, -9, 13, 6, -3, -5, 0, 3, -1;
%o A303992 (PARI) T(n, k) = polcoef(prod(j=1, n, (1-x^j)^3), k);
%o A303992 tabf(nn) = for(n=0, nn, for(k=0, 3*n*(n+1)/2, print1(T(n, k), ", ")); print)
%Y A303992 Cf. A010816, A231599, A304080.
%K A303992 sign,tabf
%O A303992 0,3
%A A303992 _Seiichi Manyama_, May 04 2018