OFFSET
1,6
COMMENTS
Primes 1 + b^32768 are a form of generalized Fermat primes.
It is conjectured that a(n) is asymptotic to 0.000177083*li(10^n)
LINKS
Yves Gallot, How many prime numbers appear in a sequence ?
EXAMPLE
a(5) = 1 because the generalized Fermat numbers F_15(b) where b<10^5 are prime only for b = 70906.
PROG
(PARI) a(n) = sum(b=1, 10^n/2-1, isprime((2*b)^32768 + 1))
CROSSREFS
KEYWORD
nonn
AUTHOR
Henryk Dabrowski, Aug 29 2012
STATUS
approved