A188549 Numbers k such that 8*k^2+1 is a prime.

3, 12, 15, 18, 21, 33, 36, 48, 51, 66, 78, 81, 93, 102, 114, 120, 132, 150, 153, 162, 180, 183, 213, 225, 228, 231, 234, 237, 243, 246, 252, 279, 282, 285, 294, 303, 318, 324, 333, 375, 378, 381, 384, 393, 396, 399, 417, 432, 450, 459, 468, 480, 489, 495, 510

Offset: 1

Author

Vincenzo Librandi, Apr 04 2011

Keywords

• nonn
• easy

Comments

Half of the even terms of A089001. - R. J. Mathar, Apr 09 2011

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A090685 (Primes of the form 8*n^2 + 1), A089001.

Programs

Magma

[n: n in [1..1800]|IsPrime(8*n^2 + 1)]; // Vincenzo Librandi, Apr 04 2011

Mathematica

Select[Range[600],PrimeQ[8#^2+1]&] (* Harvey P. Dale, Apr 11 2012 *)