%I A153450
%S A153450 1,2,6,54,6542,203280221
%N A153450 Number of primes <= 2^(2^n) = PiPrime(A001146)
%H A153450 H. J. Smith, <a href="http://harry-j-smith.com/hjsmithh/download.html#XICalc"> 
               XICalc - Extra Precision Integer Calculator.</a>
%F A153450 a(n) = PiPrime(2^(2^n))
%e A153450 a(3) = 54 because 2^(2^3) = 256 and there are 54 primes <= 256.
%o A153450 (Other) (XICalc) Pi(2^(2^n));
%Y A153450 A001146
%Y A153450 Sequence in context: A085078 A152543 A122593 this_sequence A084123 A074023 
               A000146
%Y A153450 Adjacent sequences: A153447 A153448 A153449 this_sequence A153451 A153452 
               A153453
%K A153450 nonn
%O A153450 0,2
%A A153450 Harry J. Smith (hjsmithh(AT)sbcglobal.net), Dec 27 2008