A141773 Primes of the form x^2 + 9*x*y - y^2 (as well as of the form 9*x^2 + 11*x*y + y^2).

19, 59, 89, 101, 149, 151, 179, 191, 229, 239, 251, 271, 281, 331, 349, 359, 389, 409, 421, 461, 491, 509, 569, 599, 631, 659, 661, 701, 739, 761, 769, 829, 859, 919, 971, 1019, 1021, 1039, 1069, 1109, 1171, 1181, 1249, 1259, 1279, 1291, 1301, 1361, 1381

Offset: 1

Author

Laura Caballero Fernandez, Lourdes Calvo Moguer, Maria Josefa Cano Marquez, Oscar Jesus Falcon Ganfornina and Sergio Garrido Morales (sergarmor(AT)yahoo.es), Jul 04 2008

Keywords

• nonn

Comments

Discriminant = 85. Class = 2. Binary quadratic forms a*x^2 + b*x*y + c*y^2 have discriminant d = b^2 - 4ac.

Examples

			a(1) = 19 because we can write 19 = 1^2 + 9*1*3 - 3^2.
		

References

• Z. I. Borevich and I. R. Shafarevich, Number Theory.

Links

• N. J. A. Sloane et al., Binary Quadratic Forms and OEIS: Index to related sequences, programs, references. OEIS wiki, June 2014.
• D. B. Zagier, Zetafunktionen und quadratische Körper, Springer, 1981.

Crossrefs

Cf. A141772 (d=85).

Extensions

More terms from Colin Barker, Apr 04 2015