A182922 a(n) = n! / A055773(n).

1, 1, 1, 1, 8, 8, 144, 144, 1152, 10368, 518400, 518400, 6220800, 6220800, 609638400, 9144576000, 146313216000, 146313216000, 2633637888000, 2633637888000, 52672757760000, 1106127912960000, 267682954936320000

Offset: 0

Author

Peter Luschny, Mar 05 2011

Keywords

• nonn

Comments

a(n) = n! * P(floor(n/2))/P(n), where P(n) is a primorial number (A034386).

Programs

Maple

A182922 := n -> n! / mul(k, k=select(isprime, [$iquo(n,2)+1..n])):
# Or without division:
a182922 := proc(n) local k,i,R;
R := {seq(i,i=1..n)} minus {op(select(isprime,[seq(i,i=iquo(n,2)+1..n)]))};
mul(k,k=R) end:

Mathematica

a[n_] := n!/Numerator[n!/Floor[n/2]!^4];
Table[a[n], {n, 0, 22}] (* Jean-François Alcover, Jun 18 2019 *)