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A140618 Primes of the form 20x^2+4xy+23y^2. 1
23, 47, 191, 239, 263, 311, 359, 479, 503, 647, 719, 1031, 1103, 1151, 1223, 1487, 1559, 1583, 1607, 1847, 1871, 2039, 2063, 2087, 2399, 2543, 2591, 2927, 2999, 3407, 3671, 3767, 3863, 3911, 4007, 4127, 4463, 4583, 4679, 4751, 4799, 4871 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Discriminant=-1824. Also primes of the form 23x^2+20xy+44y^2.

In base 12, the sequence is 1E, 3E, 13E, 17E, 19E, 21E, 25E, 33E, 35E, 45E, 4EE, 71E, 77E, 7EE, 85E, X3E, X9E, XEE, E1E, 109E, 10EE, 121E, 123E, 125E, 147E, 157E, 15EE, 183E, 189E, 1E7E, 215E, 221E, 229E, 231E, 239E, 247E, 26EE, 279E, 285E, 28EE, 293E, 299E, where X is for 10 and E is for 11. Moreover, the discriminant is -1080. - Walter Kehowski, May 31 2008

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

MATHEMATICA

Union[QuadPrimes[20, 4, 23, 10000], QuadPrimes[20, -4, 23, 10000]] (* see A106856 *) Note: the original QuadPrimes had a bug which could sometimes give wrong answers. This sequence should be checked (unless the coefficient of xy in the quadratic form is zero, in which case QuadPrimes gives correct answers). - N. J. A. Sloane, Jun 04 2014

CROSSREFS

Cf. A140633.

Sequence in context: A139857 A139900 A065017 * A233443 A042052 A136030

Adjacent sequences:  A140615 A140616 A140617 * A140619 A140620 A140621

KEYWORD

nonn,easy

AUTHOR

T. D. Noe, May 19 2008

STATUS

approved

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Last modified July 23 23:07 EDT 2014. Contains 244873 sequences.