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 A203581 #8 Jan 14 2013 08:53:53
%S A203581 1,19,19684,2294583564,51987957606172224,354256491848971529923455168,
%T A203581 1043097707370582731107248079473888804864,
%U A203581 1807964167474441339593635811814833549204957259332698112
%N A203581 Vandermonde sequence using x^2 + xy + y^2 applied to (2,3,...,n+1).
%C A203581 See A093883 for a discussion and guide to related sequences.
%t A203581 f[j_] := j + 1; z = 12;
%t A203581 v[n_] := Product[Product[f[j]^2 + f[j] f[k] + f[k]^2,
%t A203581 {j, 1, k - 1}], {k, 2, n}]
%t A203581 Table[v[n], {n, 1, z}] (* A203581 *)
%t A203581 Table[v[n + 1]/v[n], {n, 1, z}] (* A203582 *)
%K A203581 nonn
%O A203581 1,2
%A A203581 _Clark Kimberling_, Jan 04 2012