OFFSET
1,2
EXAMPLE
All 5 numbers 1+42,1+4242,1+424242,1+42424242 & 1+4242424242 are prime and 42
is the smallest such number so a(5)=42.
CROSSREFS
KEYWORD
base,more,nonn
AUTHOR
Farideh Firoozbakht, Apr 01 2009
STATUS
approved