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The largest four-digit composite number (17*577) not divisible by 2, 3, or 5 that yields no primes if the first digit is changed to any non-zero digit. I.e., 1809, 2809, 3809, 4809, 5809, 6809, 7809 and 8809 are all composite.

 

  Submitted: 2004-01-02 18:27:18;   Last Modified: 2008-01-30 11:28:00.



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