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A110067
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Numbers n such that 10^n + sigma(n) is prime.
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8
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OFFSET
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1,2
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COMMENTS
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All terms are of the form k^2 or 2*k^2. There is no further term up to 16000.
a(5) > 10^6 or it doesn't exist. - Robert Price, Mar 03 2015
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LINKS
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MATHEMATICA
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Do[If[PrimeQ[10^n + DivisorSigma[1, n]], Print[n]], {n, 16000}]
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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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STATUS
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approved
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