We shall define a sqube to be a number of the form, , where and are distinct primes.
For example, or .
The first five squbes are , and .
Interestingly, is also the first number for which you cannot change any single digit to make a prime; we shall call such numbers, prime-proof. The next prime-proof sqube which contains the contiguous sub-string "" is .
Find the th prime-proof sqube containing the contiguous sub-string "".
Write-up coming later
The complete problem is available here. An approach, code, and answer will be added later.