

A106863


Primes of the form x^2+xy+5y^2.


7



5, 7, 11, 17, 19, 23, 43, 47, 61, 73, 83, 101, 131, 137, 139, 149, 157, 163, 191, 197, 199, 229, 233, 239, 251, 263, 271, 277, 283, 311, 313, 347, 349, 353, 359, 367, 389, 397, 419, 443, 457, 461, 463, 467, 479, 491, 499, 503, 541, 557, 571, 577, 587, 593
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

Discriminant=19.
Also, primes of the form x^2xy+5y^2 with x and y nonnegative.
Also, primes which are a square (mod 19) (or, (mod 38)  cf. A191028).  M. F. Hasler, Jan 15 2016
Also, primes p such that Legendre(2,p) = 0 or 1.  N. J. A. Sloane, Dec 25 2017


LINKS

Vincenzo Librandi and Ray Chandler, Table of n, a(n) for n = 1..10000 [First 5000 terms from Vincenzo Librandi]
N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)


MATHEMATICA

QuadPrimes2[1, 1, 5, 10000] (* see A106856 *)


PROG

(PARI) select(p>issquare(Mod(p, 19))&&isprime(p), [1..1000]) \\ M. F. Hasler, Jan 15 2016


CROSSREFS

Primes in A035243.
Sequence in context: A155772 A258992 A020582 * A200569 A110016 A254672
Adjacent sequences: A106860 A106861 A106862 * A106864 A106865 A106866


KEYWORD

nonn,easy


AUTHOR

T. D. Noe, May 09 2005


STATUS

approved



