A162237 Primes p such that p^2+3*p+1 is not prime.

11, 13, 17, 31, 41, 61, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 127, 131, 149, 151, 167, 181, 191, 193, 197, 199, 211, 223, 227, 233, 241, 251, 269, 271, 277, 281, 283, 307, 311, 317, 331, 337, 347, 367, 383, 389, 397, 401, 409, 421, 431, 433, 439, 443

Offset: 1

Author

Vincenzo Librandi, Jun 28 2009

Keywords

• nonn
• easy

Examples

			p=11, p^2+3*p+1=155=5*31; p=13, p^2+3*p+1=209=11*19; p=17, p^2+3*p+1=341=11*31.
		

Links

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

Crossrefs

Cf. A153590.

Programs

Magma

[p: p in PrimesUpTo(500) | not IsPrime(p^2+3*p+1)]; // Vincenzo Librandi, Sep 11 2013

Mathematica

Select[Range[0, 500], PrimeQ[#] && !PrimeQ[#^2 + 3 # + 1] &] (* Vincenzo Librandi, Sep 11 2013 *)