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Search: id:A141338
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| A141338 |
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Primes of the form x^2+9*x*y-3*y^2 (as well as of the form 7*x^2+11*x*y+y^2). |
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3
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| 7, 19, 31, 67, 97, 103, 109, 157, 163, 193, 211, 283, 307, 349, 373, 379, 397, 421, 439, 541, 547, 577, 607, 661, 691, 727, 733, 751, 769, 811, 853, 877, 907, 919, 937, 997
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OFFSET
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0,1
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COMMENT
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Discriminant = 93. 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(2)=19 because we can write 19=2^2+9*2*5-3*5^2 (or 19=7*1^2+11*1*1+1^2).
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CROSSREFS
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Cf. A141339 (d=93).
Sequence in context: A068229 A071696 A114564 this_sequence A145042 A038869 A147503
Adjacent sequences: A141335 A141336 A141337 this_sequence A141339 A141340 A141341
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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 (oscfalgan(AT)yahoo.es), Jun 25 2008
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