A188719 Number of safe primes < 10^n.

2, 7, 25, 115, 670, 4324, 30657, 229568, 1775675, 14156112, 115500275, 960392564

Offset

1,1

Comments

Number of safe primes with at most n digits; or a(10^n).

Links

Table of n, a(n) for n=1..12.

Wikipedia, Safe prime

Example

a(10^2) = a(100) = #{5, 7, 11, 23, 47, 59, 83} = 7

Crossrefs

A156875, A006880, A005385

Sequence in context: A150534 A150535 A076176 * A103465 A103464 A358498

Adjacent sequences: A188716 A188717 A188718 * A188720 A188721 A188722

Keyword

nonn

Author

Krzysztof Ostrowski, Apr 09 2011

Status

approved