There are 43 3-digit prime numbers which, when reversed, also yield a prime number. (Eight of these are actually consecutive primes).

Of the 43, 15 are simply palindromes (e.g. 929), but of the remaining 14 pairs of numbers (called 'emirp's), one pair in particular exhibits two unique characteristics, one of which is rather surprising.

What are the numbers, and what are their unique characteristics?

(In reply to re(3): here are the pairs - thx Charlie by brianjn)

Well, while adding the pairs Charlie found doesn't yield much, subtraction does yield an interesting pattern, albeit nothing helpful.  Perhaps Brian, you should revisit your other work!

Posted by rod hines on 2009-01-12 14:34:44