A241808 Numbers k such that (2*k)^3 - 3 is prime.

1, 2, 4, 5, 7, 8, 13, 17, 19, 20, 37, 40, 53, 55, 58, 62, 68, 79, 89, 92, 95, 103, 112, 115, 119, 128, 137, 140, 158, 160, 169, 170, 193, 205, 214, 223, 229, 232, 235, 242, 248, 265, 272, 275, 278, 295, 313, 317, 322, 323, 337, 355, 359, 364

Offset: 1

Author

Gerasimov Sergey, Apr 29 2014

Keywords

• nonn
• easy

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A006254, A153974.

Programs

Magma

[n: n in [1..500] | IsPrime((2*n)^3 - 3)]; // Juri-Stepan Gerasimov, May 12 2014

Mathematica

Select[Range[400], PrimeQ[(2*#)^3 - 3] &] (* Amiram Eldar, Aug 29 2020 *)

PARI

is(n)=isprime((2*n)^3-3) \\ Charles R Greathouse IV, Jun 13 2017

Formula

a(n) = A153974(n)/2. - R. J. Mathar, May 14 2014