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A119986
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Least positive k such that k * 10^n + prime(n) is prime.
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0
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1, 6, 19, 5, 6, 17, 6, 6, 10, 2, 15, 17, 3, 9, 7, 48, 32, 12, 39, 9, 17, 18, 27, 1, 50, 36, 18, 3, 11, 44, 19, 45, 46, 78, 36, 36, 5, 20, 33, 41, 127, 42, 12, 63, 16, 33, 31, 42, 8, 6, 98, 57, 21, 47, 22, 91, 21, 45, 24, 1, 3, 12, 72, 57, 51, 129, 351, 8, 23, 87, 88, 108, 80, 120, 4, 3
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OFFSET
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4,2
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REFERENCES
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J. Earls & J. Rogers, 0.1361015212836455566..., Lulu Press, NY, 2006, p. 22.
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LINKS
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MATHEMATICA
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lpk[n_]:=Module[{k=1, c=10^n, p=Prime[n]}, While[!PrimeQ[k*c+p], k++]; k]; Array[ lpk, 80, 4] (* Harvey P. Dale, Sep 01 2020 *)
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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