I just wrote a second ago:

> To get that number, I'm presuming once the requisite six heads have been
> achieved, the tosser stops. That is a critical assumption.

Given further thought, this assumption is NOT critical. We don't give a hoot
what the tosser does after the first heads have been thrown. The only caveat
to that statement would be if the question had been framed as "What's the
probability of tossing 6 and only 6 heads in a row out of 20 coin tosses?"
But that wasn't the question that was asked.

Wirt Atmar