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Prime Crossed Factor Puzzle (Posted on 2023-03-18) Difficulty: 3 of 5
Find all possible pairs (x, y) of prime numbers, with x less than or equal to y, and each of x and y being less than 2023, such that:
• y divides x2 + 8 and,
• x divides y2 + 8
Provide valid reasoning as to why there are no further solutions.

*** Extra credit for an analytical solution.

Note: This puzzle is adapted from a problem appearing in the Zhautykov Olympiad.

See The Solution Submitted by K Sengupta    
Rating: 5.0000 (2 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re: Computer solution without extra credit | Comment 2 of 3 |
(In reply to Computer solution without extra credit by Larry)

(89,881)

This is why I was having such a hard time proving there were no "large" solutions - because that premise is false!  I found (2,2) and (3,17) pretty quickly and thought that since this was an Olympiad problem the rest of the answer would be to prove the lack of "large" solutions.  Now I see that is not the case and am at a loss to figure how to get to (89,881).

  Posted by Brian Smith on 2023-03-18 21:05:44
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