A105467 Number of irregular primes less than or equal to the 3^n-th prime.

0, 0, 5, 22, 91, 286, 863, 2577, 7717, 23160, 69939, 209485, 627826, 1881554, 5645226, 16936048

Offset

1,3

Comments

Limit_{n->inf.} a(n)/3^n = 1-e^(-1/2).

Links

Table of n, a(n) for n=1..16.

Mathematica

ip={ the list of irregular primes to 12 million }; Table[ Length[ Select[ip, # < Prime[3^n] &]], {n, 9}]

Crossrefs

Cf. A038833, A105458, A105462.

Sequence in context: A081892 A128566 A097138 * A208736 A050185 A216597

Adjacent sequences: A105464 A105465 A105466 * A105468 A105469 A105470

Keyword

hard,nonn,more

Author

Robert G. Wilson v, Apr 07 2005

Extensions

Terms corrected and a(10)-a(16) added by Amiram Eldar, Mar 05 2019

Status

approved