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 A139831 Primes of the form 2x^2+2xy+23y^2. 3
 2, 23, 47, 83, 107, 167, 227, 263, 347, 383, 443, 467, 503, 563, 587, 647, 683, 743, 827, 863, 887, 947, 983, 1103, 1163, 1187, 1223, 1283, 1307, 1367, 1427, 1487, 1523, 1583, 1607, 1667, 1787, 1823, 1847, 1907, 2003, 2027, 2063, 2087, 2207 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Discriminant=-180. See A139827 for more information. Except for 2, also primes of the forms 3x^2+20y^2 (A107169) and 8x^2+4xy+23y^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 Except for 2, the primes are congruent to {23, 47} (mod 60). MATHEMATICA QuadPrimes2[2, -2, 23, 10000] (* see A106856 *) PROG (MAGMA) [2] cat[ p: p in PrimesUpTo(3000) | p mod 60 in {23, 47}]; // Vincenzo Librandi, Jul 29 2012 CROSSREFS Sequence in context: A156557 A002428 A105440 * A049592 A054679 A057621 Adjacent sequences:  A139828 A139829 A139830 * A139832 A139833 A139834 KEYWORD nonn,easy AUTHOR T. D. Noe, May 02 2008 STATUS approved

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Last modified February 21 01:15 EST 2019. Contains 320364 sequences. (Running on oeis4.)