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AoPS Wiki:Problem of the Day/August 14, 2011

< AoPS Wiki:Problem of the Day
Revision as of 11:20, 14 August 2011 by Mrdavid445 (talk | contribs) (Created page with "Find all natural numbers <math>n</math> for which each natural number written with <math>n-1</math>'ones' and one 'seven' is prime.")
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Find all natural numbers $n$ for which each natural number written with $n-1$'ones' and one 'seven' is prime.

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