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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
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
Sequence in context: A172220 A255151 A184607 * A220158 A085377 A219298
KEYWORD
nonn
AUTHOR
Henryk Dabrowski, Aug 21 2012
STATUS
approved

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