A162237 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

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

EXAMPLE

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.

MATHEMATICA

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

PROG

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

CROSSREFS