Re: Trying to recursively define a double factorial

*To*: mathgroup at smc.vnet.net*Subject*: [mg126530] Re: Trying to recursively define a double factorial*From*: Bob Hanlon <hanlonr357 at gmail.com>*Date*: Thu, 17 May 2012 04:10:33 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <201205160820.EAA23026@smc.vnet.net>

myF1[0] = myF1[1] = 1; myF1[n_Integer?Positive] := n*myF1[n - 2] And @@ Table[n!! == Factorial2[n] == myF1[n], {n, 0, 256}] True Bob Hanlon On Wed, May 16, 2012 at 4:20 AM, Jorge Cantu <monsterbone at msn.com> wrote: > My goal here is to define a recursive function for a double factorial. The domain of this function is the set of positive integers. For a positive even integer n the value DF[n] is the product of all positive even integers which are <n. For a positive odd integer n the value DF[n] is the product of all positive odd integers which are <n. > > I wanna make a recursive function of this double factorial without If(and other similar statements). Here is my work so far: > > > Clear[MyF1, n]; > MyF1[1] = 1; > MyF1[n_Integer] /; (n > 0) := MyF1[n] = n*MyF1[n - 1] > > Table[MyF1[k], {k, (*integer*), (*integer*)}] > > > > How do I do this?

**References**:**Trying to recursively define a double factorial***From:*Jorge Cantu <monsterbone@msn.com>