Question: Check if number of $a$ are prime with just two tapes in Tuning machine.
I'm not quite sure how to check it but what I've got so far is:
First tape will be the input. For example $aaaaa$
Second tape will be checking the numbers $2$ till $n-1$, meaning $4$ for this example.
We start checking them both from the beginning of the tapes, we write '$aa$' in the second tape, making some checks which I'm not sure, if we fail with these checks, start again but now with '$aaa$', and then lastly '$aaaa$'.