I guess for the prime number levels you expected people to make a sieve type thing using 2, 3, 5, and 7. I just made a machine that can tell if any non-negative is prime, though it runs slowly as it checks if a number is divisible by every number smaller than it and greater than 1.
I am pretty sure there is a bug in the recursion. I have what I believe is a solution for number 19, but it hangs. Since we can't watch the recursion steps, nor enter our own inputs, I stepped through the execution on paper and got the correct answer. I therefore think there is an error.
I seem to have an infinite loop on the jahooma test case on number 19, but since it is in the recursion step, I can't bugtest. We need a way to enter our own inputs.
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