A214289 Numbers k such that 2*k^3 - 1 is prime.

3, 4, 6, 10, 16, 21, 24, 25, 31, 34, 43, 46, 54, 55, 58, 61, 64, 69, 81, 90, 91, 93, 99, 108, 120, 126, 130, 139, 141, 154, 166, 178, 181, 189, 198, 199, 205, 210, 213, 214, 223, 241, 249, 255, 259, 273, 285, 295, 331, 334, 336, 346, 348, 351, 354, 366, 369, 370, 373, 375, 376, 378

Offset: 1

Author

Vincenzo Librandi, Jul 25 2012

Keywords

• nonn
• easy

Links

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

Crossrefs

Cf. A177105.

Programs

Magma

[n: n in [1..400]|IsPrime(2*n^3-1)];

Mathematica

Select[Range[0,1000],PrimeQ[2*#^3-1]&]

PARI

is(n)=isprime(2*n^3-1) \\ Charles R Greathouse IV, Jun 13 2017

Formula

A177105(n) = 2*n^3 - 1. - R. J. Mathar, Aug 20 2019