OFFSET
1,3
EXAMPLE
a(3)=2 because out of the first 1000 primes, only two have first and last digits 9, 919 and 929.
CROSSREFS
KEYWORD
hard,nonn,base
AUTHOR
Enoch Haga, Oct 16 2008
EXTENSIONS
Better definition from R. J. Mathar, Aug 04 2010
Edited and corrected by N. J. A. Sloane, Aug 16 2010
a(7)-a(10) from D. S. McNeil, Aug 29 2010
STATUS
approved