This is a symbol for a triple factorial.
We have n!!! = n * (n - 3) * (n - 6) * ... * 1
Our subtraction of 3 never goes below one.
12!!! = 12 * 9 * 6 * 3
We have n!!! = n * (n - 3) * (n - 6) * ... * 1
Our subtraction of 3 never goes below one.
12!!! = 12 * 9 * 6 * 3