login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A215701 Number of primes of the form 1 + b^2048 for 1 < b < 10^n. 0
0, 0, 1, 4, 40, 276 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
COMMENTS
Primes 1 + b^2048 are a form of generalized Fermat primes.
It is conjectured that a(n) is asymptotic to 0.00352764*li(10^n)
LINKS
EXAMPLE
a(4) = 4 because the generalized Fermat numbers F_11(b) where b<10^4 are prime only for b = 150, 2558, 4650, 4772.
PROG
(PARI) a(n) = sum(b=1, 10^n/2-1, isprime((2*b)^2048+1))
CROSSREFS
Sequence in context: A119635 A367557 A283660 * A366667 A212699 A061318
KEYWORD
nonn
AUTHOR
Henryk Dabrowski, Aug 21 2012
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified March 28 05:02 EDT 2024. Contains 371235 sequences. (Running on oeis4.)