1234567 Seven numbers with 5040 permutations.

Factorial correlation extension

N factorial representation of any natural number greater than 1;

or

Factorial factor is an operation symbol invented by Keyston Kramp (1760 ~1826) in 1808, and it is a mathematical term.

The factorial of a positive integer is the product of all positive integers less than or equal to this number, and the factorial of 0 is 1. The factorial writing of natural number n! . In 1808, Keyston Kaman introduced this symbol.

Which is n! =1× 2× 3× ...× n. The factor can also be defined recursively: 0! = 1，n！ =(n- 1)！ ×n .