A165637 Primes p such that (p^2-3)/2 is not a prime number.

2, 17, 43, 53, 59, 61, 71, 83, 89, 107, 113, 127, 131, 137, 139, 149, 163, 167, 173, 179, 181, 191, 193, 199, 223, 229, 241, 251, 269, 271, 277, 281, 283, 311, 313, 317, 347, 373, 379, 383, 401, 419, 421, 431, 433, 439, 457, 461, 467, 479, 499, 503, 523, 541, 557, 563

Offset: 1

Author

Vincenzo Librandi, Sep 23 2009

Keywords

• nonn
• easy

Examples

			For p=17=a(2), (17^2-3)/2=143 is not a prime. For p=43=a(3), (43^2-3)/2=923 is not a prime.
		

Links

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

Programs

Magma

[p: p in PrimesUpTo(600)| not IsPrime((p^2-3) div 2)]; // Vincenzo Librandi, Sep 12 2013

Mathematica

Select[Prime[Range[200]], !PrimeQ[(#^2 - 3) / 2]&] (* Harvey P. Dale, Dec 09 2011 *)

Formula

A000040 \ A110589. - R. J. Mathar, Sep 26 2009

Extensions

Extended by R. J. Mathar, Sep 26 2009