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A153768
Numbers n such that n, 8n-9 and 8n+9 are primes.
3
11, 29, 31, 109, 199, 251, 269, 379, 419, 521, 599, 601, 661, 881, 991, 1091, 1231, 1289, 1789, 1831, 1861, 1901, 1949, 2239, 2689, 2969, 3181, 3251, 3301, 3359, 3499, 3779, 3821, 4099, 4201, 4339, 4561, 4651, 4679, 4789, 4871, 5281, 5471, 5641, 5659
OFFSET
1,1
LINKS
EXAMPLE
For n=11, even 8n-9=79 and 8n+9=97 are primes, therefore 11 is in the sequence.
MATHEMATICA
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 *)
Select[Prime[Range[6000]], PrimeQ[8 # - 9] && PrimeQ[8 # + 9] &] (* Vincenzo Librandi, Apr 05 2013 *)
Select[Prime[Range[800]], AllTrue[8#+{9, -9}, PrimeQ]&] (* Harvey P. Dale, Apr 05 2023 *)
PROG
(Magma) [p: p in PrimesUpTo(6000) | IsPrime(8*p-9) and IsPrime(8*p+9)]; // Vincenzo Librandi, Apr 05 2013
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Jan 01 2009
EXTENSIONS
241 replaced by 251 and extended by R. J. Mathar, Jan 07 2009
STATUS
approved