312
This number is a composite.
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312 is the only number m less than 30000 such that
prime(k*m) + k*m is prime for k = 1, 11, 1111, 111111, 11111111, and 111111111. [Firoozbakht]
Submitted: 2004-02-10 18:14:40; Last Modified: 2008-01-30 17:28:00.
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