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A139992
Primes of the form 20x^2+20xy+47y^2.
2
47, 167, 383, 503, 647, 887, 983, 1223, 1487, 1823, 1847, 2063, 2663, 2687, 2903, 3023, 3167, 3407, 3527, 3863, 4007, 4583, 4703, 5087, 5927, 6047, 6263, 6863, 7103, 7607, 7703, 7727, 8447, 8543, 8783, 9623, 9743, 9887, 10223, 10247, 10463
OFFSET
1,1
COMMENTS
Discriminant=-3360. See A139827 for more information.
Also primes of the forms 47x^2+40xy+80y^2 and 47x^2+42xy+63y^2. See A140633. - T. D. Noe, May 19 2008
LINKS
Vincenzo Librandi and Ray Chandler, Table of n, a(n) for n = 1..10000 [First 1000 terms from Vincenzo Librandi]
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)
FORMULA
The primes are congruent to {47, 143, 167, 383, 503, 647} (mod 840).
MATHEMATICA
QuadPrimes2[20, -20, 47, 10000] (* see A106856 *)
PROG
(Magma) [p: p in PrimesUpTo(12000) | p mod 840 in [47, 143, 167, 383, 503, 647]]; // Vincenzo Librandi, Aug 03 2012
CROSSREFS
Sequence in context: A132251 A078857 A216827 * A142916 A253351 A253344
KEYWORD
nonn,easy
AUTHOR
T. D. Noe, May 02 2008
STATUS
approved