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Primes that remain prime through 4 iterations of function f(x) = 2x + 9.
1

%I #23 Sep 08 2022 08:44:47

%S 11,31,1181,2521,3701,4211,4931,8221,8461,9871,11981,13121,14591,

%T 16381,16901,21991,23021,34961,36781,37691,43991,44531,45181,46021,

%U 46051,52321,57601,59921,62081,75391,89071,92051,95621,105361,115211,124171,128461

%N Primes that remain prime through 4 iterations of function f(x) = 2x + 9.

%C Primes p such that 2*p+9, 4*p+27, 8*p+63 and 16*p+135 are also primes. - _Vincenzo Librandi_, Aug 04 2010

%H Harvey P. Dale, <a href="/A023306/b023306.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Prime[Range[12500]],And@@PrimeQ[Rest[NestList[2#+9&,#,4]]]&] (* _Harvey P. Dale_, Jan 01 2014 *)

%o (Magma) [n: n in [1..1000000] | IsPrime(n) and IsPrime(2*n+9) and IsPrime(4*n+27) and IsPrime(8*n+63) and IsPrime(16*n+135)] // _Vincenzo Librandi_, Aug 04 2010

%K nonn

%O 1,1

%A _David W. Wilson_