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A103095
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Numbers n such that 9*10^n + 2*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.
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1
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1, 3, 4, 15, 153, 322, 471, 561, 664, 2157, 3697, 14875, 19270, 22095
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OFFSET
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1,2
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COMMENTS
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Also numbers n such that (83*10^n+43)/9 is prime.
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LINKS
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FORMULA
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MATHEMATICA
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Do[ If[ PrimeQ[(83*10^n + 43)/9], Print[n]], {n, 0, 10000}]
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CROSSREFS
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KEYWORD
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more,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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