# Anybody know how to express odd factorials?

#### YoYoBabyYo

##### Senior member
I am trying to find a formula to express odd or even factorials, for example:

1*3*5*7*...*n

or

2*4*6*8...*n

I searched google, but had no luck. Does anybody have a clue what the formula is?

#### Chaotic42

##### Lifer
Well, 2n-1 is always odd and 2n is always even.

Are you looking for a mathematical forumla, or a way to do it in programming?

#### YoYoBabyYo

##### Senior member
Originally posted by: SmoochyTX

I had no luck with Google. Either that or my searching skills suck.

#### SmoochyTX

##### Lifer
Originally posted by: YoYoBabyYo
Originally posted by: SmoochyTX

I had no luck with Google. Either that or my searching skills suck.

Well um....

#### vrbaba

##### Diamond Member
n even: (n/2)!*2^(n/2)

#### vrbaba

##### Diamond Member
n!/(((n-1)/2)!*2^((n-1)/2))

#### YoYoBabyYo

##### Senior member
Huh! Let me try those out!

#### vrbaba

##### Diamond Member
Originally posted by: YoYoBabyYo
Huh! Let me try those out!

Updated n odd, check above

#### quakefiend420

##### Lifer
YOyoYO has a kid?

#### YoYoBabyYo

##### Senior member
Originally posted by: vrbaba
Originally posted by: YoYoBabyYo
Huh! Let me try those out!

Updated n odd, check above

I was going to ask about the odd, but the even seemed to have worked! May I ask how you knew? :thumbsup:

Sorry to break the bad news, but YoyoYo does not have a kid.

#### vrbaba

##### Diamond Member
Originally posted by: YoYoBabyYo
Originally posted by: vrbaba
Originally posted by: YoYoBabyYo
Huh! Let me try those out!

Updated n odd, check above

I was going to ask about the odd, but the even seemed to have worked! May I ask how you knew? :thumbsup:

Sorry to break the bad news, but YoyoYo does not have a kid.

courtesy Chuckywang <-- :beer: