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A172122 Primes p such that 7*p^2+7*p+1 is also prime. 1

%I #11 Sep 08 2022 08:45:50

%S 2,5,17,29,59,197,227,257,317,359,467,509,569,587,797,929,1097,1187,

%T 1259,1307,1439,1637,1697,1847,1877,1997,2027,2069,2099,2237,2297,

%U 2399,2459,2477,2657,2687,2729,2939,3167,3359,3407,3467,3659,3677,4019,4079

%N Primes p such that 7*p^2+7*p+1 is also prime.

%H Vincenzo Librandi, <a href="/A172122/b172122.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Prime[Range[3000]], PrimeQ[7 #^2 + 7 # + 1]&] (* _Vincenzo Librandi_, Apr 16 2013 *)

%o (Magma) [p: p in PrimesUpTo(4100) | IsPrime(7*p^2 + 7*p + 1)]; // _Vincenzo Librandi_, Apr 16 2013

%Y Cf. A171139.

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Jan 26 2010

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Last modified March 28 04:58 EDT 2024. Contains 371235 sequences. (Running on oeis4.)