A028885 Numbers k such that k^2 - 8 is prime.

5, 7, 9, 11, 17, 19, 21, 23, 25, 31, 35, 37, 45, 49, 51, 53, 65, 67, 81, 87, 91, 93, 101, 103, 115, 117, 119, 121, 123, 129, 133, 135, 143, 145, 147, 149, 161, 163, 173, 177, 185, 187, 191, 203, 205, 207, 213, 227, 229, 231, 235, 241, 245, 247, 257, 259, 261, 269

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• easy

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000
• P. De Geest, Palindromic Quasipronics of the form n(n+x)

Crossrefs

Cf. A028886 (associated primes).

Programs

Magma

[n: n in [3..1000] | IsPrime(n^2-8)]; // Vincenzo Librandi, Nov 18 2010

Mathematica

Select[Range[3,1200],PrimeQ[#^2-8]&] (* Vladimir Joseph Stephan Orlovsky, Feb 27 2011 *)

PARI

is(n)=isprime(n^2-8) \\ Charles R Greathouse IV, Jun 06 2017

Extensions

Checked by Neven Juric (neven.juric(AT)apis-it.hr), Feb 04 2008