OFFSET
1,3
COMMENTS
Primes 1 + b^64 are a form of generalized Fermat primes.
It is conjectured that a(n) is asymptotic to 0.0616053*li(10^n)
LINKS
Yves Gallot, How many prime numbers appear in a sequence ?
EXAMPLE
a(3) = 8 because the Fermat numbers F_6(b) where b<10^3 are prime only for b = 102, 162, 274, 300, 412, 562, 592, 728.
PROG
(PARI) a(n) = sum(b=1, 10^n/2-1, isprime((2*b)^64+1))
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Henryk Dabrowski, Aug 01 2012
EXTENSIONS
a(8)-a(9) from Kellen Shenton, Aug 09 2020
STATUS
approved