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 A298983 #54 Mar 11 2018 05:09:58 %S A298983 1,2,-2,6,-3,-3,8,0,-8,0,20,-5,-5,-5,-5,12,6,-6,-12,-6,6,42,-7,-7,-7, %T A298983 -7,-7,-7,32,0,0,0,-32,0,0,0,54,0,0,-27,0,0,-27,0,0,40,10,-10,10,-10, %U A298983 -40,-10,10,-10,10,110,-11,-11,-11,-11,-11,-11,-11,-11,-11,-11 %N A298983 Triangle read by rows T(n,k) giving coefficients in expansion of Product_{j=1..n} (1-x^j)^2 mod x^(n+1)-1. %H A298983 Seiichi Manyama, <a href="/A298983/b298983.txt">Rows n = 0..139, flattened</a> %F A298983 T(n,k) = (n+1) * Sum_{d | gcd(n+1,n+1-k)} d*mu((n+1)/d) for 0 <= k <= n. %F A298983 So T(n,0) = A002618(n+1) and T(n,n) = A055615(n+1). %e A298983 Triangle begins: %e A298983 k 0 1 2 3 4 5 6 %e A298983 n %e A298983 0 1; %e A298983 1 2, -2; %e A298983 2 6, -3, -3; %e A298983 3 8, 0, -8, 0; %e A298983 4 20, -5, -5, -5, -5; %e A298983 5 12, 6, -6, -12, -6, 6; %e A298983 6 42, -7, -7, -7, -7, -7, -7; %Y A298983 Cf. A002618, A055615, A282634, A300628. %K A298983 sign,tabl %O A298983 0,2 %A A298983 _Seiichi Manyama_, Mar 10 2018