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Factorial2
(!!)
n
!!
gives the double factorial of
n
.
MORE INFORMATION
Mathematical function, suitable for both symbolic and numerical manipulation.
.
n
!!
is a product of even numbers for
n
even, and odd numbers for
n
odd.
Factorial2
can be evaluated to arbitrary numerical precision.
Factorial2
automatically threads over lists.
EXAMPLES
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Basic Examples
(2)
Integer values:
In[1]:=
Out[1]=
In[2]:=
Out[2]=
Evaluate numerically:
In[1]:=
Out[1]=
Scope
(5)
Generalizations & Extensions
(3)
Applications
(1)
Properties & Relations
(4)
Possible Issues
(2)
Neat Examples
(3)
SEE ALSO
Factorial
Gamma
Pochhammer
TUTORIALS
Combinatorial Functions
RELATED LINKS
MathWorld
The Wolfram Functions Site
NKS|Online
(
A New Kind of Science
)
MORE ABOUT
Combinatorial Functions
Gamma Functions and Related Functions
Recurrence and Sum Functions
New in 1
© 2008 Wolfram Research, Inc.
.
EXAMPLES
Basic Examples 
Scope 