A138030 - OEIS

%I #7 Dec 02 2016 01:14:14

%S 85864769,198479579,305192579,2400025739,7606886429,7755909149,

%T 10378311899,16744125509,17029114499,17117793089,17574340739,

%U 26089808579,28889527679,43390196519,45424068359,52179617159,54293956289,56838102179,65639153579,66655116659

%N Numbers n such that n remains prime through 8 iterations of function f(x) = 2x + 1.

%F a(n) == 89 or 329 (mod 330). - _John Cerkan_, Nov 30 2016

%t Select[Prime[Range[10^8]],PrimeQ[a1=2*#+1]&&PrimeQ[a2=2*a1+1]&&PrimeQ[a3=2*a2+1]&&PrimeQ[a4=2*a3+1]&&PrimeQ[a5=2*a4+1]&&PrimeQ[a6=2*a5+1]&&PrimeQ[a7=2*a6+1]&&PrimeQ[a8=2*a7+1] &]

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, May 01 2008