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%I #28 Aug 24 2024 18:44:19
%S 5,11,17,251,563,21011
%N Prime numbers p > 3 such that 2^p - 9 is prime.
%C Let W = 2^p - 9 and s = (W+7)/(2*p), then 3^s == 4 (mod W) for terms 1..6.
%t Select[Prime[Range[3,565]],PrimeQ[2^#-9]&] (* The program generates the first five terms of the sequence. *) (* _Harvey P. Dale_, Aug 24 2024 *)
%o (PARI)
%o forprime(p=5, 10^5, W= 2^p-9; if(ispseudoprime(W), print1(p, ", ")))
%Y Cf. A059610.
%K nonn,more
%O 1,1
%A _Dmitry Ezhov_, Mar 07 2017