Here is my answer:

the first coin is even odds
the second coin would be 6 out of 17 2.8333
the third coin would be 6 out of 16 2.6666
at the second casino the first coin would
be even odds
the second coin would again be 2.8333
and the third would be again 2.6666
so my quess would be:

2.8333 times 2.6666 times 2.833 times 2.6666
assuming we are using four decimal for the
odds comes to 57.0854.
if you are using infinately for 2.8333 and 2.6666
it will be a little more dificult to calculate.

Am I close?