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Primes p such that p^2 + 2*p - 4 is also prime.
3

%I #12 Oct 05 2024 14:35:38

%S 3,5,7,11,13,23,31,37,41,43,71,73,101,131,151,163,167,173,181,197,211,

%T 233,251,263,277,283,317,353,373,383,401,431,433,467,491,547,557,571,

%U 587,593,607,643,653,701,727,733,761,823,857,881,907,911,937,983,991

%N Primes p such that p^2 + 2*p - 4 is also prime.

%H Vincenzo Librandi, <a href="/A154319/b154319.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Prime[Range[1000]], PrimeQ[#^2 + 2*# - 4]&] (* _Vincenzo Librandi_, Oct 30 2012 *)

%o (Magma) [p: p in PrimesUpTo(1500)| IsPrime(p^2 + 2*p - 4)]; // _Vincenzo Librandi_, Oct 30 2012

%Y Cf. A154320, A154321.

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Jan 07 2009