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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A215699 Number of primes of the form 1 + b^512 for 1 < b < 10^n. 4
 0, 1, 1, 28, 160, 1247 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 COMMENTS Primes 1 + b^512 are a form of generalized Fermat primes. It is conjectured that a(n) is asymptotic to 0.0146271*li(10^n) LINKS Table of n, a(n) for n=1..6. Yves Gallot, Status of the smallest base values yielding Generalized Fermat primes Yves Gallot, How many prime numbers appear in a sequence ? Yves Gallot, A Problem on the Conjecture Concerning the Distribution of Generalized Fermat Prime numbers (a new method for the search for large primes) EXAMPLE a(3) = 1 because the generalized Fermat numbers F_9(b) where b<10^3 are prime only for b = 46. PROG (PARI) a(n) = sum(b=1, 10^n/2-1, isprime((2*b)^512+1)) CROSSREFS Cf. A215047, A215048, A215049, A215050, A215051, A215057, A215058, A215698. Sequence in context: A172220 A255151 A184607 * A220158 A085377 A219298 Adjacent sequences: A215696 A215697 A215698 * A215700 A215701 A215702 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.

Last modified April 19 02:28 EDT 2024. Contains 371782 sequences. (Running on oeis4.)