How to get factorial of an odd number?

[#1]

fact(n)  is a chart general numeric function that returns the factorial of a positive integer n - 1×2×3×4×...×n. Is there  any way I can get the factorial of a positive odd number, for example,  1×3×5×7×...×(2m−1). Thanks

[#2 · Accepted solution]

I finally found answer for this questions: = fact(n)/(fact((x-1)/2)* pow(2, (x-1)/2))