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A141184
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Primes of the form x^2+5*x*y-5*y^2 (as well as of the form x^2+7*x*y+y^2).
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7
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19, 31, 61, 79, 109, 139, 151, 181, 199, 211, 229, 241, 271, 331, 349, 379, 409, 421, 439, 499, 541, 571, 601, 619, 631, 661, 691, 709, 739, 751, 769, 811, 829, 859, 919, 991, 1009, 1021, 1039, 1051, 1069, 1129, 1171, 1201, 1231, 1249, 1279, 1291, 1321, 1381, 1399, 1429, 1459
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Discriminant = 45. Class = 2. Binary quadratic forms a*x^2+b*x*y+c*y^2 have discriminant d=b^2-4ac and gcd(a,b,c)=1
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REFERENCES
| Borevich and Shafaewich, Number Theory.
D. B. Zagier, Zetafunktionen und quadratische Koerper.
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LINKS
| Juan Arias-de-Reyna, Table of n, a(n) for n = 1..10000
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EXAMPLE
| a(1)=19 because we can write 19=3^2+5*3*1-5*1^2 (or 19=1^2+7*1*2+2^2).
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CROSSREFS
| Cf. A141185 (d=45), A033212 (Primes of form x^2+15*y^2.) A038872 (d=5). A141131 (d=8). A141122, A141123 (d=12). A038883 (d=13). A038889 (d=17). A141111, A141112 (d=65).
Sequence in context: A104485 A192505 A033212 * A104227 A032743 A106861
Adjacent sequences: A141181 A141182 A141183 * A141185 A141186 A141187
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KEYWORD
| nonn
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AUTHOR
| Laura Caballero Fernandez, Lourdes Calvo Moguer, Maria Josefa Cano Marquez, Oscar Jesus Falcon Ganfornina and Sergio Garrido Morales (oscfalgan(AT)yahoo.es), Jun 12 2008
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