A140618 - OEIS

A140618

Primes of the form 20x^2+4xy+23y^2.

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

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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 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[QuadPrimes220, 4, 23, 10000], QuadPrimes2[20, -4, 23, 10000]] (* see A106856 *)

CROSSREFS

Cf. A140633.

Sequence in context: A139857 A139900 A065017 * A042052 A136030 A054693

Adjacent sequences: A140615 A140616 A140617 * A140619 A140620 A140621

KEYWORD

nonn,easy

AUTHOR

T. D. Noe, May 19 2008

STATUS

approved