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 A140622 Primes of the form 21x^2+12xy+76y^2. 1
 109, 229, 349, 421, 541, 661, 709, 1021, 1549, 1669, 1789, 1861, 2221, 2269, 2749, 3061, 3109, 3229, 3469, 3541, 4621, 4789, 4909, 5101, 5701, 5869, 6229, 6469, 6661, 6781, 6949, 7741, 7789, 8101, 8221, 8461, 8821, 9349, 9661, 9781, 9901 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Discriminant=-6240. Also primes of the form 45x^2+30xy+109y^2. In base 12, the sequence is 91, 171, 251, 2E1, 391, 471, 4E1, 711, X91, E71, 1051, 10E1, 1351, 1391, 1711, 1931, 1971, 1X51, 2011, 2071, 2811, 2931, 2X11, 2E51, 3371, 3491, 3731, 38E1, 3X31, 3E11, 4031, 4591, 4611, 4831, 4911, 4X91, 5131, 54E1, 5711, 57E1, 5891, where X is for 10 and E is for 11. Moreover, the discriminant is -3740. - Walter Kehowski, Jun 01 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) MATHEMATICA Union[QuadPrimes2[21, 12, 76, 10000], QuadPrimes2[21, -12, 76, 10000]] (* see A106856 *) CROSSREFS Cf. A140633. Sequence in context: A142697 A142777 A142797 * A278784 A256380 A063342 Adjacent sequences:  A140619 A140620 A140621 * A140623 A140624 A140625 KEYWORD nonn,easy AUTHOR T. D. Noe, May 19 2008 STATUS approved

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Last modified July 27 20:33 EDT 2021. Contains 346308 sequences. (Running on oeis4.)