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Palindrome ponder (Posted on 2012-09-23) Difficulty: 2 of 5
Determine the smallest base ten positive palindrome with exactly 4 distinct prime factors.

No Solution Yet Submitted by K Sengupta    
Rating: 3.0000 (1 votes)

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re(2): No Subject | Comment 7 of 8 |
(In reply to re: No Subject by broll)

That "shortcut" is not particularly reliable.  All even-digit palindromes are divisible by 11, but only 1 out 11 odd digit palindromes is divisible by 11.  It is just sheer chance that 858 is divisible by 11, so the shortcut appears to work.  

From Charlie's list, for example, 24242 =  2 * 17 * 23 *  31 is the smallest 5 digit palindrome with exactly 4 distinct prime factors, but it would not be found by this "shortcut".

  Posted by Steve Herman on 2012-09-23 20:45:00
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