OFFSET
1,5
COMMENTS
Lim_{n->inf.} a(n)/2^n = 1 - e^(-1/2).
MATHEMATICA
ip={ the list of irregular primes to 12 million }; Table[ Length[ Select[ip, # <= Prime[2^n] &]], {n, 19}]
CROSSREFS
KEYWORD
hard,nonn,more
AUTHOR
Robert G. Wilson v, Apr 07 2005
EXTENSIONS
Data corrected and a(20)-a(26) added by Amiram Eldar, Mar 05 2019
STATUS
approved