probability of straight flush in omaha

[JoshD]

I am having trouble with this counting problem. Could someone give an accurate probability for getting a straight flush in Omaha assuming that i always see the river.

[irchans]

I did a quick calculation for the probability of a Royal Flush and got

0.0000923446 = 4.*C[5, 2]*C[52 - 5, 2]*C[52 - 7, 2]/ (C[52, 4]*C[48, 5])

where

C[x,y] = x!/y!/(x-y)!

I figure that the chance of a straight flush is near 10 times 0.0000923446.