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A139854
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Primes of the form 3x^2 + 40y^2.
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3
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3, 43, 67, 163, 283, 307, 523, 547, 643, 787, 883, 907, 1123, 1483, 1627, 1723, 1747, 1867, 1987, 2083, 2203, 2347, 2467, 2683, 2707, 2803, 3067, 3163, 3187, 3307, 3547, 3643, 3907, 4003, 4027, 4243, 4363, 4483, 4507, 4603, 4723, 4987, 5107
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OFFSET
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1,1
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COMMENTS
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Discriminant=-480. See A139827 for more information.
Except for 3, also primes of the form 27x^2+12xy+28y^2. See A140633. - T. D. Noe, May 19 2008
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LINKS
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FORMULA
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Except for 3, the primes are congruent to {43, 67} (mod 120).
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MATHEMATICA
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QuadPrimes2[3, 0, 40, 10000] (* see A106856 *)
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PROG
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(Magma) [3] cat [ p: p in PrimesUpTo(6000) | p mod 120 in {43, 67}]; // Vincenzo Librandi, Jul 29 2012
(PARI) list(lim)=my(v=List(), w, t); for(x=1, sqrtint(lim\3), w=3*x^2; for(y=0, sqrtint((lim-w)\40), if(isprime(t=w+40*y^2), listput(v, t)))); Set(v) \\ Charles R Greathouse IV, Feb 22 2017
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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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STATUS
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approved
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