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A216529
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Numbers n such that (10^n-1)/9 is prime and can be written in the form a^2 + 3*b^2.
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0
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OFFSET
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1,1
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COMMENTS
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The exponent is congruent to 1 mod 3.
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LINKS
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PROG
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(PARI) is(n)=my(t=10^n\9); ispseudoprime(t) && #bnfisintnorm(bnfinit(z^2+z+1), t) \\ Charles R Greathouse IV, Jun 13 2017
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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