Here is a brief update. The list is Straights, 8-card straight draws, and 4-card straight draws.

3-Gap: S = 64 ; 8SD = 512 ; 4SD = 2624
2-Gap: S = 128 ; 8SD = 1024 ; 4SD = 3072
1-Gap: S = 192 ; 8SD = 1536 ; 4SD = 3648
0-Gap: S = 256 ; 8SD = 2048 ; 4SD = 4224

You can get each probability by dividing by 19600, the total number of flops possible.

Also, I'm working now on "nut" straights. Unless you have AT, it's impossible to have the nut straight draw. With a connector like 98, 75% of straights are the nuts, 5/8's of the 8-card straight draws are the nuts, and 2/3's of 4-card straight draws are the nuts.

I've always wondered why connectors are so much more valuable than gappers (understood the theory, but wanted to know the details). I'll start a new thread with the results when I'm (a) done and (b) sure they are correct.

For those math geeks interested, the number of straights and 8-card straight draws make a nice linear progression. 2-gappers have twice as many straights and 8-card draws as 3-gappers, and 1-gappers have 3x as many, and so on. It seems the 4-card ones should have a pattern, too, so I might have some errors. I'm rechecking everything.