FACTDOUBLE function

FACTDOUBLE(number) FACTDOUBLE(number)

number — Number or { Number }

The input number.

Returns — Number or { Number }

The double factorial of a number.

Returns the double factorial of a number, denoted n!!. The double factorial for the odd number n is defined as the product of all positive, odd integers which are less than or equal to n.

Example

FACTDOUBLE(9)FACTDOUBLE(9)

Returns 945 (9 * 7 * 5 * 3 * 19 * 7 * 5 * 3 * 1).