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 A140613 Primes of the form 7*x^2 + 6*x*y + 39*y^2. 2
 7, 79, 127, 151, 271, 439, 607, 919, 967, 1063, 1231, 1327, 1399, 1447, 1471, 1663, 1759, 1999, 2239, 2287, 2383, 2503, 2551, 2647, 2719, 2767, 2791, 3079, 3319, 3343, 3511, 3559, 3583, 3607, 3823, 3847, 3967, 4111, 4231, 4567, 4639, 4663 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Discriminant=-1056. Also primes of the form 7x^2 + 4xy + 76y^2. In base 12, the sequence is 7, 67, X7, 107, 1X7, 307, 427, 647, 687, 747, 867, 927, 987, X07, X27, E67, 1027, 11X7, 1367, 13X7, 1467, 1547, 1587, 1647, 16X7, 1727, 1747, 1947, 1E07, 1E27, 2047, 2087, 20X7, 2107, 2267, 2287, 2367, 2467, 2547, 2787, 2827, 2847, where X is 10 and E is 11. Moreover, the discriminant is -740. - Walter Kehowski, Jun 01 2008 LINKS Vincenzo Librandi, N. J. A. Sloane and Ray Chandler, Table of n, a(n) for n = 1..10000 [First 1000 terms from Vincenzo Librandi, next 5218 terms from N. J. A. Sloane] N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references) J. Voight, Quadratic forms that represent almost the same primes, Math. Comp., Vol. 76 (2007), pp. 1589-1617. See Example 6.1. - N. J. A. Sloane, Jun 07 2014 FORMULA These are exactly the primes congruent to one of 7, 79, 127, 151, or 175 (mod 264) [Voight]. - N. J. A. Sloane, Jun 07 2014 MATHEMATICA Union[QuadPrimes2[7, 6, 39, 10000], QuadPrimes2[7, -6, 39, 10000]] (* see A106856 *) PROG (PARI) select(n-> n%264==7 || n%264==79 || n%264==127 || n%264==151 || n%264==175, primes(100000)) \\ N. J. A. Sloane, Jun 07 2014 CROSSREFS Cf. A140633. Sequence in context: A106107 A020471 A065902 * A139945 A023285 A135051 Adjacent sequences:  A140610 A140611 A140612 * A140614 A140615 A140616 KEYWORD nonn,easy AUTHOR T. D. Noe, May 19 2008 EXTENSIONS Incorrect Mathematica program deleted by N. J. A. Sloane, Jun 07 2014 STATUS approved

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Last modified April 13 18:53 EDT 2021. Contains 342939 sequences. (Running on oeis4.)