%I A105465
%S A105465 0,0,0,1,5,15,47,95,205,405,822,1625,3243,6453,12798,25715,51778,103315,
%T A105465 206646
%N A105465 Number of irregular primes less than or equal to the 2^n-th prime.
%C A105465 Limit_{n->inf.} a(n)/2^n = 1-e^(-1/2).
%t A105465 ip={ the list of irregular primes to 12 million }; Table[ Length[ Select[ip, 
               # < Prime[2^n] &]], {n, 19}]
%Y A105465 Cf. A105456, A105460.
%Y A105465 Sequence in context: A058425 A079798 A037504 this_sequence A089040 A126944 
               A077841
%Y A105465 Adjacent sequences: A105462 A105463 A105464 this_sequence A105466 A105467 
               A105468
%K A105465 hard,nonn
%O A105465 1,5
%A A105465 Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 07 2005