A028876 Numbers k such that k^2 - 5 is prime.

4, 6, 8, 12, 14, 16, 22, 24, 32, 34, 36, 38, 42, 44, 46, 52, 58, 64, 72, 74, 78, 82, 94, 102, 112, 116, 122, 132, 144, 152, 164, 166, 168, 174, 176, 182, 184, 186, 188, 198, 204, 212, 222, 226, 232, 234, 236, 252, 262, 264, 278, 284, 288, 292, 298, 302, 318, 324

Offset: 1

Author

Patrick De Geest

Keywords

• nonn
• easy

Links

• G. C. Greubel, Table of n, a(n) for n = 1..1000
• P. De Geest, Palindromic Quasipronics of the form n(n+x)
• Eric Weisstein's World of Mathematics, Near-Square Prime

Crossrefs

Cf. A028875, A028877.

Programs

Magma

[n: n in [2..1000] |IsPrime(n^2 - 5 )]; // Vincenzo Librandi, Nov 18 2010

Mathematica

Select[Range[400], PrimeQ[#^2 - 5] &] (* Alonso del Arte, Aug 27 2013 *)

PARI

is(n)=isprime(n^2-5) \\ Charles R Greathouse IV, Jun 06 2017