A143827 Numbers k such that 8*k^2 - 1 is prime.

1, 2, 3, 4, 5, 9, 11, 12, 14, 17, 18, 19, 21, 23, 25, 26, 28, 31, 32, 38, 40, 46, 49, 51, 54, 56, 59, 63, 66, 67, 70, 77, 79, 80, 82, 86, 89, 93, 94, 96, 98, 100, 102, 103, 107, 110, 114, 116, 119, 121, 124, 128, 133, 135, 137, 140, 144, 147, 150, 152, 156, 161, 166

Offset: 1

Author

Artur Jasinski, Sep 02 2008

Keywords

• nonn
• changed

Comments

Contains the even terms of A066049 divided by 2. - R. J. Mathar, Sep 04 2008

Crossrefs

Cf. A090686, A090684.

Programs

Mathematica

p = 8; a = {}; Do[k = p x^2 - 1; If[PrimeQ[k], AppendTo[a, x]], {x, 1, 1000}]; a

PARI

is(n)=isprime(8*n^2-1) \\ Charles R Greathouse IV, Feb 17 2017