OFFSET
1,4
COMMENTS
Primes 1 + b^4096 are a form of generalized Fermat primes.
It is conjectured that a(n) is asymptotic to 0.00205697*li(10^n)
LINKS
Yves Gallot, How many prime numbers appear in a sequence ?
EXAMPLE
a(4) = 2 because the generalized Fermat numbers F_12(b) where b<10^4 are prime only for b = 1534, 7316.
PROG
(PARI) a(n) = sum(b=1, 10^n/2-1, isprime((2*b)^4096+1))
CROSSREFS
KEYWORD
nonn
AUTHOR
Henryk Dabrowski, Aug 21 2012
STATUS
approved