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A038877
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Primes p such that 6 is not a square mod p.
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3
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7, 11, 13, 17, 31, 37, 41, 59, 61, 79, 83, 89, 103, 107, 109, 113, 127, 131, 137, 151, 157, 179, 181, 199, 223, 227, 229, 233, 251, 257, 271, 277, 281, 347, 349, 353, 367, 373, 397, 401, 419, 421, 439, 443, 449
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OFFSET
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1,1
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COMMENTS
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Also primes p such that p divides 3^(p-1)/2 + 2^(p-1)/2.
Also primes p such that p divides 6^(p-1)/2 + 1.
Also primes p such that p divides 6^(p-1)/2 + 4^(p-1)/2. (End)
Inert rational primes in the field Q(sqrt(6)). - Alonso del Arte, Oct 14 2012
Primes congruent to 7, 11, 13, or 17 mod 24.
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LINKS
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FORMULA
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EXAMPLE
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17 is in the sequence because there is no solution to the equation x^2 - 6y = 17 in integers.
19 is NOT in the sequence because x^2 - 6y = 19 has solutions in integers, as does x^2 - 6y^2 = 19, e.g., x = 5, y = 1, and therefore (5 - sqrt(6))*(5 + sqrt(6)) = 19.
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MATHEMATICA
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Select[Prime@Range[120], JacobiSymbol[6, #] == -1 &] (* Vincenzo Librandi, Sep 08 2012 *)
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PROG
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(PARI)
forprime(p=2, 500, if(kronecker(6, p)==-1, print1(p, ", ")));
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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