46.1 Factorial

Factorial( n )

Factorial returns the factorial n! of the positive integer n, which is defined as the product 1 * 2 * 3 * .. * n.

n! is the number of permutations of a set of n elements. 1/n! is the coefficient of x^n in the formal series e^x, which is the generating function for factorial.

    gap> List( [0..10], Factorial );
    [ 1, 1, 2, 6, 24, 120, 720, 5040, 40320, 362880, 3628800 ]
    gap> Factorial( 30 );
    265252859812191058636308480000000 

PermutationsList (see PermutationsList) computes the set of all permutations of a list.

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