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 A203238 #6 Mar 30 2012 18:58:05
%S A203238 1,-2,-20,112,1504,-14208,-244992,3274752,69267456,-1199554560,
%T A203238 -30106091520,640796590080,18622701895680,-470423898685440,
%U A203238 -15541046083584000,454463600984064000,16822958391558144000,-559005839520694272000
%N A203238 a(n)=(n-1)-st elementary symmetric function of the first n terms of (2, -4, 6, -8, 10, ...).
%t A203238 f[k_] := (2 k) (-1)^(k + 1)
%t A203238 t[n_] := Table[f[k], {k, 1, n}]
%t A203238 a[n_] := SymmetricPolynomial[n - 1, t[n]]
%t A203238 Table[a[n], {n, 1, 22}] (* A203238 *)
%Y A203238 Cf. A181174.
%K A203238 sign
%O A203238 1,2
%A A203238 _Clark Kimberling_, Dec 30 2011