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 A023235 Numbers n such that n and 9n + 8 both prime. 20
 5, 7, 11, 19, 29, 47, 61, 71, 79, 89, 97, 107, 127, 131, 139, 151, 167, 179, 181, 211, 229, 251, 271, 317, 337, 397, 401, 419, 421, 449, 461, 467, 487, 541, 547, 557, 571, 599, 601, 607, 659, 677, 701, 709, 727, 739, 761, 811, 827, 839, 877, 881, 907, 929, 971, 1051 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 MATHEMATICA lst={}; Do[p=Prime[n]; If[PrimeQ[9*p+8], AppendTo[lst, p]], {n, 6!}]; lst (* Vladimir Joseph Stephan Orlovsky, Mar 10 2009 *) Select[Prime[Range[900]], PrimeQ[9 # + 8] &] (* Vincenzo Librandi, May 21 2014 *) PROG (MAGMA) [n: n in [0..1000] | IsPrime(n) and IsPrime(9*n+8)]; // Vincenzo Librandi, Nov 20 2010 (PARI) is(n)=isprime(9*n+8) && isprime(n) \\ Charles R Greathouse IV, Jul 02 2013 (MAGMA) [p: p in PrimesUpTo(1100)| IsPrime(9*p+8)]; // Vincenzo Librandi, May 21 2014 CROSSREFS Sequence in context: A182121 A072825 A045440 * A118918 A019376 A159080 Adjacent sequences:  A023232 A023233 A023234 * A023236 A023237 A023238 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified October 15 15:03 EDT 2019. Contains 328030 sequences. (Running on oeis4.)