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It's easy to make an exhaustive computer search in base 10 by starting with one-digit primes and trying to add digits to the start (left-truncatable) or end (right-truncatable) while keeping it a prime. I and many others have done it. I think my exhaustive search took less than a second on a PC. It
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studies a case where the truncation doesn't have to end with a one-digit prime (or equivalently that addition of digits can start from a multidigit prime). There I wrote: "96842946512633189183337876922083307 is the smallest (and only known) prime which can be truncated more times than the largest
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article does not address if there are prime truncatable both right and left, or for that matter a proof they eithr do or do not exist. --
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All but four of these are also left-and-right truncatable: 2, 3, 5, 7, 23, 37, 53, 73, 373, 3137, 3797. Would these be "three-sided"? --
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gets harder for bases significantly above 10 when there are a lot of possible digits to add. There are left-truncatable base counts in
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I have added "two-sided primes", primes which are both left-truncatable and right-truncatable, to the article.
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left-truncatable prime". The truncation ends with 76922083307. The next number 6922083307 is composite.
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The rules must be changed to give something computationally challenging in base 10.
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How can it be known that there is a bound on the number of truncatable primes?
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