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Primes p such that p^2 - 8 is also prime.
1

%I #22 Jun 25 2022 12:53:46

%S 5,7,11,17,19,23,31,37,53,67,101,103,149,163,173,191,227,229,241,257,

%T 269,271,313,347,353,359,367,373,383,431,467,479,487,523,541,563,577,

%U 599,613,619,647,653,661,733,761,773,823,829,859,863,919,941,1061,1087

%N Primes p such that p^2 - 8 is also prime.

%C The first appearances of 2..6 consecutive primes in the sequence are: {31,37}, {5, 7, 11}, {353, 359, 367, 373}, {1293199, 1293203, 1293233, 1293239, 1293247}, {3982031, 3982037, 3982057, 3982067, 3982073, 3982079}.

%C Initial terms of the sets of exactly 6 consecutive primes: {3982031, 5495989, 33057589, 255414437, 495180067, 558985507}.

%H K. D. Bajpai, <a href="/A258992/b258992.txt">Table of n, a(n) for n = 1..10000</a>

%e From _K. D. Bajpai_, Jun 18 2015: (Start)

%e a(3) = 11: both 11 and 11^2 - 8 = 113 are prime.

%e a(4) = 17: both 17 and 17^2 - 8 = 281 are prime.

%e (End)

%t Select[Prime[Range[5000]], PrimeQ[#^2-8]&] (* _K. D. Bajpai_, Jun 18 2015 *)

%o (PARI) lista(nn) = forprime(p=2, nn, if (isprime(p^2-8), print1(p, ", "))); \\ _Michel Marcus_, Jun 16 2015

%o (Magma) [p: p in PrimesUpTo(5000) | IsPrime(p^2-8)]; // _K. D. Bajpai_, Jun 18 2015

%Y Cf. A062718, A137270.

%K nonn

%O 1,1

%A _Zak Seidov_, Jun 16 2015