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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A140620 Primes of the form 23x^2+4xy+68y^2. 2
23, 263, 503, 647, 887, 1223, 1583, 1823, 1847, 2063, 2207, 2447, 2687, 2903, 3407, 3527, 3623, 3767, 4007, 4463, 4703, 4943, 4967, 5087, 5303, 5807, 5903, 5927, 6263, 6863, 7127, 7487, 7583, 7823, 8087, 8423, 8447, 9623, 9767, 10007, 10247 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Discriminant=-6240. Also primes of the form 23x^2+18xy+207y^2.

In base 12, the sequence is 1E, 19E, 35E, 45E, 61E, 85E, XEE, 107E, 109E, 123E, 133E, 14EE, 167E, 181E, 1E7E, 205E, 211E, 221E, 239E, 26EE, 287E, 2X3E, 2X5E, 2E3E, 309E, 343E, 34EE, 351E, 375E, 3E7E, 415E, 43EE, 447E, 463E, 481E, 4X5E, 4X7E, 569E, 579E, 595E, 5E1E, where X is 10 and E is 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[23, 4, 68, 10000], QuadPrimes2[23, -4, 68, 10000]] (* see A106856 *)

CROSSREFS

Cf. A140633.

Sequence in context: A022618 A042018 A125411 * A002681 A240876 A142220

Adjacent sequences:  A140617 A140618 A140619 * A140621 A140622 A140623

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 | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 20 20:14 EDT 2019. Contains 321352 sequences. (Running on oeis4.)