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Factorials and Powers (Posted on 2009-04-22) Difficulty: 3 of 5
Determine all possible pair(s) (X, Y), with X being a prime and Y being a positive integer, that satisfy this equation:

(X-1)! + 1 = XY

No Solution Yet Submitted by K Sengupta    
Rating: 4.0000 (2 votes)

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Question Related problem Comment 8 of 8 |
http://perplexus.info/show.php?pid=6393&cid=42523

Here we were specifically concerned with any perfect square, not just a power of X.  I tried to prove there were few solutions.  Could similar methods work here?

Note: if Y is even we can use the same difference of squares idea.

  Posted by Jer on 2009-04-25 01:39:08
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