Factorial

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Definition

Let be a nonnegative integer. The factorial of , denoted , and read as n factorial, is defined as the product of all the natural numbers from to . Note that is defined as .

is also the order of the symmetric group, or the group of all permutations, on a set of size .

Behavior

The ID of the sequence in the Online Encyclopedia of Integer Sequences is A000142

Initial values

Here are the values of for small : .

Related notions