OFFSET
0,3
COMMENTS
Next term is greater than 3*10^8.
EXAMPLE
For k=0,1,...,5 4^4^k + 106908087 are prime and 106908087 is the smallest number with this property so a(5)=106908087.
CROSSREFS
KEYWORD
hard,more,nonn
AUTHOR
Farideh Firoozbakht, May 13 2007
STATUS
approved