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Search: id:A141773
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| A141773 |
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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). |
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3
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| 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
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OFFSET
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1,1
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COMMENT
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Discriminant = 85. 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
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Borevich and Shafaewich, Number Theory.
D. B. Zagier, Zetafunktionen und quadratische Koerper.
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EXAMPLE
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a(1)=19 because we can write 19 = 1^2+9*1*3-3^2
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CROSSREFS
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Cf. A141772 (d=85).
Sequence in context: A041706 A042619 A141887 this_sequence A031375 A146351 A139920
Adjacent sequences: A141770 A141771 A141772 this_sequence A141774 A141775 A141776
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KEYWORD
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nonn
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AUTHOR
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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
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