%I A023302
%S A023302 2,89,179,53639,53849,61409,63419,66749,126839,127139,143609,167729,
%T A023302 186149,206369,254279,268049,296099,340919,405269,422069,446609,539009,
%U A023302 594449,607319,658349,671249,725009,775949,810539,810809,812849,819509
%N A023302 Numbers n such that n remains prime through 4 iterations of function 
               f(x) = 2x + 1.
%t A023302 Select[Prime[Range[10^4*4]], PrimeQ[a1=2*#+1]&&PrimeQ[a2=2*a1+1]&&PrimeQ[a3=2*a2+1]&&PrimeQ[a4=2*a3+1] 
               &] (from Vladimir Orlovsky (4vladimir(AT)gmail.com), May 01 2008)
%Y A023302 Cf. (A005384 and A005385), A007700, A023272, A023330, A057331, A005602.
%Y A023302 Sequence in context: A105268 A139881 A161676 this_sequence A041967 A024239 
               A076532
%Y A023302 Adjacent sequences: A023299 A023300 A023301 this_sequence A023303 A023304 
               A023305
%K A023302 nonn
%O A023302 1,1
%A A023302 David W. Wilson (davidwwilson(AT)comcast.net)