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A183187
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Numbers k such that 10^(2k+1)-10^k-1 is prime.
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47
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OFFSET
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1,1
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COMMENTS
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REFERENCES
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C. Caldwell and H. Dubner, "Journal of Recreational Mathematics", Volume 28, No. 1, 1996-97, pp. 1-9.
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LINKS
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FORMULA
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MATHEMATICA
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Do[If[PrimeQ[10^(2n + 1) - 10^n - 1], Print[n]], {n, 3000}]
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PROG
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CROSSREFS
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KEYWORD
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nonn,more,base
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AUTHOR
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STATUS
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approved
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