login
This site is supported by donations to The OEIS Foundation.

 

Logo

Many excellent designs for a new banner were submitted. We will use the best of them in rotation.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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 *)

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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Content is available under The OEIS End-User License Agreement .

Last modified April 16 21:07 EDT 2014. Contains 240627 sequences.