%I #17 Apr 05 2023 17:41:49
%S 11,29,31,109,199,251,269,379,419,521,599,601,661,881,991,1091,1231,
%T 1289,1789,1831,1861,1901,1949,2239,2689,2969,3181,3251,3301,3359,
%U 3499,3779,3821,4099,4201,4339,4561,4651,4679,4789,4871,5281,5471,5641,5659
%N Numbers n such that n, 8n-9 and 8n+9 are primes.
%H Vincenzo Librandi, <a href="/A153768/b153768.txt">Table of n, a(n) for n = 1..1000</a>
%e For n=11, even 8n-9=79 and 8n+9=97 are primes, therefore 11 is in the sequence.
%t lst={}; Do[p=Prime[n]; If[PrimeQ[8*p-9]&&PrimeQ[8*p+9],AppendTo[lst,p]],{n,7!}]; lst (* _Vladimir Joseph Stephan Orlovsky_, Aug 16 2009 *)
%t Select[Prime[Range[6000]], PrimeQ[8 # - 9] && PrimeQ[8 # + 9] &] (* _Vincenzo Librandi_, Apr 05 2013 *)
%t Select[Prime[Range[800]],AllTrue[8#+{9,-9},PrimeQ]&] (* _Harvey P. Dale_, Apr 05 2023 *)
%o (Magma) [p: p in PrimesUpTo(6000) | IsPrime(8*p-9) and IsPrime(8*p+9)]; // _Vincenzo Librandi_, Apr 05 2013
%Y Cf. A153766, A153767, A153762.
%K nonn,easy
%O 1,1
%A _Vincenzo Librandi_, Jan 01 2009
%E 241 replaced by 251 and extended by _R. J. Mathar_, Jan 07 2009