A173641 - OEIS

%I #16 Sep 08 2022 08:45:50

%S 3,5,7,13,17,47,67,73,97,167,193,293,317,373,463,487,503,593,607,677,

%T 787,823,827,1087,1613,1637,1987,2477,2543,2687,2777,2833,2903,2957,

%U 3023,3583,3593,3917,4093

%N Primes p such that p^2+4 and p^2-6 are both prime.

%C p^2+4 and p^2-6 are both primes if a(n)^2+4 is in the sequence A172240 such that A172240(n) - 10 is also prime.

%H Vincenzo Librandi, <a href="/A173641/b173641.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Prime[Range[800]], PrimeQ[#^2 + 4]&& PrimeQ[#^2 - 6]&] (* _Vincenzo Librandi_, Apr 16 2013 *)

%o (Sage) A173641 = list(p for p in primes(10^5) if is_prime(p^2+4) and is_prime(p^2-6))

%o (Magma) [p: p in PrimesUpTo(4100) | IsPrime(p^2+4)and IsPrime(p^2-6)]; // _Vincenzo Librandi_, Apr 16 2013

%K nonn,easy

%O 1,1

%A _Giovanni Teofilatto_, Nov 24 2010

%E Corrected and extended by _D. S. McNeil_, Nov 24 2010