

A145712


Number of primes p in the range 9 < p <= prime(10^n) that have most significant and least significant decimal digit both equal to 9.


3




OFFSET

1,3


LINKS

Table of n, a(n) for n=1..10.


EXAMPLE

a(3)=2 because out of the first 1000 primes, only two have first and last digits 9, 919 and 929.


CROSSREFS

Cf. A145709 A145710 A145711 A145713
Sequence in context: A013478 A049333 A140162 * A259141 A065664 A244926
Adjacent sequences: A145709 A145710 A145711 * A145713 A145714 A145715


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



