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 A033215 Primes of form x^2+21*y^2. 24
 37, 109, 193, 277, 337, 373, 421, 457, 541, 613, 673, 709, 757, 877, 1009, 1033, 1093, 1117, 1129, 1201, 1213, 1297, 1381, 1429, 1453, 1549, 1597, 1621, 1789, 1801, 1873, 1933, 2017, 2053, 2137, 2221 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 REFERENCES David A. Cox, "Primes of the Form x^2 + n y^2", Wiley, 1989. LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 N. J. A. Sloane et al., Binary Quadratic Forms and OEIS (Index to related sequences, programs, references) FORMULA Equivalently, primes congruent to {1, 25, or 37} (mod 84). - T. D. Noe, Apr 29 2008 [See e.g. Cox, p. 36. - N. J. A. Sloane, May 27 2014] MATHEMATICA QuadPrimes[1, 0, 21, 10000] (* see A106856 *) Note: the original QuadPrimes had a bug which could sometimes give wrong answers. This sequence should be checked (unless the coefficient of xy in the quadratic form is zero, in which case QuadPrimes gives correct answers). - N. J. A. Sloane, Jun 04 2014 CROSSREFS Cf. A139643. Sequence in context: A139934 A142051 A171833 * A195316 A176549 A118536 Adjacent sequences:  A033212 A033213 A033214 * A033216 A033217 A033218 KEYWORD nonn,easy AUTHOR STATUS approved

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