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 A139830 Primes of the form 7x^2+6xy+7y^2. 2
 7, 23, 47, 103, 127, 167, 223, 263, 367, 383, 463, 487, 503, 607, 647, 727, 743, 823, 863, 887, 967, 983, 1063, 1087, 1103, 1223, 1303, 1327, 1367, 1423, 1447, 1487, 1543, 1567, 1583, 1607, 1663, 1783, 1823, 1847, 2063, 2087, 2143, 2207, 2287 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Discriminant=-160. See A139827 for more information. Also primes of the forms 7x^2+2xy+23y^2 and 7x^2+4xy+12y^2. See A140633. - T. D. Noe, May 19 2008 LINKS Vincenzo Librandi and Ray Chandler, Table of n, a(n) for n = 1..10000 [First 1000 terms from Vincenzo Librandi] N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references) FORMULA The primes are congruent to {7, 23} (mod 40). MATHEMATICA Union[QuadPrimes2[7, 6, 7, 10000], QuadPrimes2[7, -6, 7, 10000]] (* see A106856 *) PROG (Magma) [ p: p in PrimesUpTo(3000) | p mod 40 in {7, 23}]; // Vincenzo Librandi, Jul 29 2012 CROSSREFS Sequence in context: A184882 A073577 A348230 * A153210 A185955 A158035 Adjacent sequences: A139827 A139828 A139829 * A139831 A139832 A139833 KEYWORD nonn,easy AUTHOR T. D. Noe, May 02 2008 STATUS approved

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Last modified April 16 17:00 EDT 2024. Contains 371749 sequences. (Running on oeis4.)