A243704 Primes represented by the indefinite quadratic form -x^2+13xy+9y^2.

31, 41, 61, 251, 349, 379, 389, 401, 419, 431, 449, 461, 491, 619, 631, 739, 769, 811, 821, 829, 1009, 1061, 1171, 1181, 1229, 1231, 1279, 1289, 1321, 1361, 1451, 1471, 1499, 1601, 1699, 1721, 1759, 1861, 2081, 2131, 2239, 2339, 2341, 2411, 2551, 2579, 2591, 2789

Offset

1,1

Comments

Discriminant 205.

4*a(n) has the form 205*y^2 - z^2, where z = 2*x-13*y. [Bruno Berselli, Jun 20 2014]

Links

Table of n, a(n) for n=1..48.

N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references)

Prog

(PARI)
fc(a, b, c, M) = {
my(t1=List(), t2);
forprime(p=2, prime(M),
t2 = qfbsolve(Qfb(a, b, c), p);
if(t2 != 0, listput(t1, p))
);
Vec(t1)
};
fc(-1, 13, 9, 600)

Crossrefs

Primes in A243703.

Sequence in context: A040991 A089721 A089442 * A381092 A060327 A202286

Adjacent sequences: A243701 A243702 A243703 * A243705 A243706 A243707

Keyword

nonn

Author

N. J. A. Sloane, Jun 17 2014

Status

approved