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%I #18 Sep 08 2022 08:45:17
%S 7,11,19,31,59,61,79,101,151,179,229,311,359,389,409,521,709,719,751,
%T 809,971,1039,1061,1151,1171,1201,1361,1459,1481,1669,1699,1811,1949,
%U 1999,2131,2341,2371,2411,2609,2671,2711,2791,2851,3019,3041,3061,3119
%N Primes p such that 2p - 9 and 2p + 9 are both primes.
%F p, 2p-9 and 2p+9 all are positive and are primes (hence we omit p=2).
%t Select[Range[7,6000], PrimeQ[ # ] && PrimeQ[2# + 9] && PrimeQ[2# - 9] &]
%t okQ[n_]:=Module[{c=2n},PrimeQ[c+9]&&PrimeQ[c-9]]; Select[Prime[ Range[5,500]],okQ] (* _Harvey P. Dale_, Apr 25 2011 *)
%o (Magma) [p: p in PrimesUpTo(3200)| IsPrime(2*p+9) and IsPrime(2*p-9) ]; // _Vincenzo Librandi_, Jan 28 2011
%K nonn
%O 1,1
%A _Zak Seidov_, Feb 16 2005
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