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 A203316 #9 Nov 26 2021 06:32:47
%S A203316 1,4,96,480,20160,129024,8294400,1423319040,8453652480,2463635865600,
%T A203316 89117289676800,660834091008000,63038756487168000,
%U A203316 20712734274355200000,4023397460155878604800,27460572284725493760000
%N A203316 a(n) = v(n+1)/(2*v(n)), where v=A203315.
%t A203316 f[j_] := Prime[j + 1]; z = 17;
%t A203316 v[n_] := Product[Product[f[k] - f[j], {j, 1, k - 1}], {k, 2, n}]
%t A203316 d[n_] := Product[(i - 1)!, {i, 1, n}]
%t A203316 Table[v[n], {n, 1, z}] (* A203315 *)
%t A203316 Table[v[n + 1]/(2 v[n]), {n, 1, z - 1}] (* A203316 *)
%t A203316 Table[v[n]/d[n], {n, 1, 20}] (* A203317 *)
%Y A203316 Cf. A203315, A203317, A000040.
%K A203316 nonn,easy
%O A203316 1,2
%A A203316 _Clark Kimberling_, Jan 01 2012
%E A203316 Definition corrected by _Georg Fischer_, Nov 26 2021