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 A141178 Primes of the form 3*x^2+x*y-3*y^2 (as well as of the form 3*x^2+7*x*y+y^2). 6
 3, 7, 11, 37, 41, 47, 53, 67, 71, 73, 83, 101, 107, 127, 137, 139, 149, 151, 157, 173, 181, 197, 211, 223, 229, 233, 263, 269, 271, 293, 307, 317, 337, 349, 359, 367, 373, 379, 397, 419, 433, 443, 491, 509, 521, 571, 593, 599, 601, 613, 617, 619, 641, 659, 673 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Discriminant = 37. Class = 1. Binary quadratic forms a*x^2+b*x*y+c*y^2 have discriminant d=b^2-4ac and gcd(a,b,c)=1 REFERENCES Z. I. Borevich and I. R. Shafarevich, Number Theory. Academic Press, NY, 1966. LINKS Jean-François Alcover, Table of n, a(n) for n = 1..10000 N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references) D. B. Zagier, Zetafunktionen und quadratische Körper, Springer-Verlag Berlin Heidelberg, 1981. EXAMPLE a(3) = 11 because we can write 11 = 3*2^2+2*1-3*1^2 (or 11 = 3*1^2+7*1*1+1^2). MATHEMATICA Reap[For[p = 2, p < 1000, p = NextPrime[p], If[FindInstance[p == 3*x^2 + x*y - 3*y^2, {x, y}, Integers, 1] =!= {}, Print[p]; Sow[p]]]][[2, 1]] (* or: *) Select[Prime[Range], # == 37 || MatchQ[Mod[#, 37], Alternatives[1, 3, 4, 7, 9, 10, 11, 12, 16, 21, 25, 26, 27, 28, 30, 33, 34, 36]]&](* Jean-François Alcover, Oct 25 2016, updated Oct 30 2016 *) CROSSREFS Cf. A038872 (d=5). A038873 (d=8). A068228, A141123 (d=12). A038883 (d=13). A038889 (d=17): A141111, A141112 (d=65). Primes in A035267. A subsequence of (and may possibly coincide with) A038913. - R. J. Mathar, Jul 22 2008 For a list of sequences giving numbers and/or primes represented by binary quadratic forms, see the "Binary Quadratic Forms and OEIS" link. Sequence in context: A051919 A119175 A038913 * A106966 A191027 A139599 Adjacent sequences:  A141175 A141176 A141177 * A141179 A141180 A141181 KEYWORD nonn AUTHOR Laura Caballero Fernandez, Lourdes Calvo Moguer, Maria Josefa Cano Marquez, Oscar Jesus Falcon Ganfornina and Sergio Garrido Morales (marcanmar(AT)alum.us.es), Jun 12 2008 STATUS approved

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Last modified January 27 22:40 EST 2021. Contains 340489 sequences. (Running on oeis4.)