%I A023330
%S A023330 89,63419,127139,405269,810809,1069199,1122659,1178609,1333889,1598699,
%T A023330 1806089,1958249,2164229,2245319,2329469,2606069,2848949,3241289,3339989,
%U A023330 3784199,3962039,4088879,4328459,4444829,4658939,4664249,4894889,4897709
%N A023330 Numbers n such that n remains prime through 5 iterations of function 
               f(x) = 2x + 1.
%t A023330 Select[Prime[Range[10^5]], PrimeQ[a1=2*#+1]&&PrimeQ[a2=2*a1+1]&&PrimeQ[a3=2*a2+1]&&PrimeQ[a4=2*a3+1]&&PrimeQ[\
               a5=2*a4+1] &] (from Vladimir Orlovsky (4vladimir(AT)gmail.com), May 
               01 2008)
%Y A023330 Cf. (A005384 and A005385), A007700, A023272, A023302, A057331, A005602.
%Y A023330 Sequence in context: A086695 A056568 A167398 this_sequence A059766 A033513 
               A128872
%Y A023330 Adjacent sequences: A023327 A023328 A023329 this_sequence A023331 A023332 
               A023333
%K A023330 nonn
%O A023330 1,1
%A A023330 David W. Wilson (davidwwilson(AT)comcast.net)