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

0,5

Comments

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

Links

Table of n, a(n) for n=0..22.

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 *)

Crossrefs

Sequence in context: A255006 A074191 A090630 * A135808 A320915 A298905

Adjacent sequences: A182919 A182920 A182921 * A182923 A182924 A182925

Keyword

nonn

Author

Peter Luschny, Mar 05 2011

Status

approved