A203316 a(n) = v(n+1)/(2*v(n)), where v=A203315.

1, 4, 96, 480, 20160, 129024, 8294400, 1423319040, 8453652480, 2463635865600, 89117289676800, 660834091008000, 63038756487168000, 20712734274355200000, 4023397460155878604800, 27460572284725493760000

Offset: 1

Author

Clark Kimberling, Jan 01 2012

Keywords

• nonn
• easy

Crossrefs

Cf. A203315, A203317, A000040.

Programs

Mathematica

f[j_] := Prime[j + 1]; z = 17;
v[n_] := Product[Product[f[k] - f[j], {j, 1, k - 1}], {k, 2, n}]
d[n_] := Product[(i - 1)!, {i, 1, n}]
Table[v[n], {n, 1, z}]                  (* A203315 *)
Table[v[n + 1]/(2 v[n]), {n, 1, z - 1}] (* A203316 *)
Table[v[n]/d[n], {n, 1, 20}]            (* A203317 *)

Extensions

Definition corrected by Georg Fischer, Nov 26 2021