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Combinatorial Functions
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Subfactorial
Subfactorial
[
n
]
gives the number of permutations of
n
objects that leave no object fixed.
MORE INFORMATION
Mathematical function, suitable for both symbolic and numerical manipulation.
For non-integer
n
, the numerical value of
Subfactorial
[
n
]
is given by
Gamma
[
n
+1, -1]/
E
.
Subfactorial
can be evaluated to arbitrary numerical precision.
A permutation in which no object appears in its natural place is called a derangement.
Subfactorial
automatically threads over lists.
Subfactorial
[0]
gives 1.
EXAMPLES
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Basic Examples
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(6)
Applications
(1)
Properties & Relations
(2)
Neat Examples
(1)
SEE ALSO
Factorial
Permutations
MORE ABOUT
Combinatorial Functions
New in 6.0: Number Theory & Integer Functions
New in 6
© 2008 Wolfram Research, Inc.
EXAMPLES
Basic Examples 
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