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Prime numbers p > 3 such that 2^p - 9 is prime.
0

%I #32 Jan 27 2025 21:01:02

%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.

%C a(7) > 3480081 using A059610. - _Michael S. Branicky_, Jan 27 2025

%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 Prime terms of A059610.

%K nonn,more

%O 1,1

%A _Dmitry Ezhov_, Mar 07 2017