

A105465


Number of irregular primes less than or equal to the 2^nth prime.


2



0, 0, 0, 1, 6, 16, 47, 96, 206, 406, 823, 1626, 3244, 6454, 12798, 25715, 51779, 103315, 206649, 412883, 825395, 1650179, 3299610, 6600347, 13201348, 26403834
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OFFSET

1,5


COMMENTS

Lim_{n>inf.} a(n)/2^n = 1  e^(1/2).


LINKS

Table of n, a(n) for n=1..26.


MATHEMATICA

ip={ the list of irregular primes to 12 million }; Table[ Length[ Select[ip, # <= Prime[2^n] &]], {n, 19}]


CROSSREFS

Cf. A000928, A033844, A105456, A105460.
Sequence in context: A126360 A264545 A296855 * A288572 A301978 A275585
Adjacent sequences: A105462 A105463 A105464 * A105466 A105467 A105468


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



