A105468 Number of irregular primes less than or equal to the 10^n-th prime.

0, 30, 392, 3935, 39400, 393737, 3933421, 39339651

Offset: 1

Author

Robert G. Wilson v, Apr 07 2005

Keywords

• hard
• nonn
• more

Comments

Limit_{n->inf.} a(n)/10^n -> 1-e^(-1/2).

Crossrefs

Cf. A000928, A006988, A105463.

Programs

Mathematica

ip={ the list of irregular primes to 12 million }; Table[ Length[ Select[ip, # <= Prime[10^n] &]], {n, 5}]

Extensions

Data corrected and a(6)-a(8) added by Amiram Eldar, Mar 05 2019