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 A076257 #8 Jun 24 2014 01:08:32
%S A076257 1,-2,0,6,0,-2,-24,0,24,0,120,0,-240,0,24,-720,0,2400,0,-720,0,5040,0,
%T A076257 -25200,0,15120,0,-720,-40320,0,282240,0,-282240,0,40320,0,362880,0,
%U A076257 -3386880,0,5080320,0,-1451520,0,40320,-3628800,0,43545600,0,-91445760,0,43545600,0
%N A076257 Coefficients of the polynomials in the numerator of 1/(1+x^2) and its successive derivatives, starting with the coefficient of the highest power of x.
%C A076257 Denominator of n-th derivative is (1+x^2)^(n+1), whose coefficients are the binomial coefficients, A007318.
%F A076257 For 0<=k<=n, let a(n, k) be the coefficient of x^k in the numerator of the n-th derivative of 1/(1+x^2). If n+k is even, a(n, k) = (-1)^((n+k)/2)*n!*binomial(n+1, k); if n+k is odd, a(n, k)=0.
%e A076257 The coefficients of the numerators starting with the coefficient of the highest power of x are 1; -2,0; 6,0,-2; -24,0,24,0; ...
%t A076257 a[n_, k_] := Coefficient[Expand[Together[(1+x^2)^(n+1)*D[1/(1+x^2), {x, n}]]], x, k]; Flatten[Table[a[n, k], {n, 0, 10}, {k, n, 0, -1}]]
%Y A076257 Cf. A076256, A076741, A076743.
%K A076257 sign,tabl,easy
%O A076257 0,2
%A A076257 _Mohammad K. Azarian_, Nov 05 2002
%E A076257 Edited by _Dean Hickerson_, Nov 28 2002