A139993 Primes of the form 21x^2+40y^2.

61, 181, 229, 349, 661, 829, 1021, 1069, 1669, 1741, 1861, 2029, 2341, 2749, 3181, 3541, 3709, 4021, 4261, 4549, 4861, 5101, 5701, 5869, 6229, 6709, 6781, 6949, 7069, 7549, 7621, 7741, 7789, 8221, 8389, 8461, 8581, 8629, 9421, 9901, 10069

Offset: 1

Author

T. D. Noe, May 02 2008

Keywords

• nonn
• easy

Comments

Discriminant=-3360. See A139827 for more information.

Also primes of the form 45x^2+30xy+61y^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)

Programs

Magma

[p: p in PrimesUpTo(12000) | p mod 840 in [61, 181, 229, 349, 661, 829]]; // Vincenzo Librandi, Aug 03 2012

Mathematica

QuadPrimes2[21, 0, 40, 10000] (* see A106856 *)

Formula

The primes are congruent to {61, 181, 229, 349, 661, 829} (mod 840).