OFFSET
1,2
COMMENTS
a(8) > 10^5. - Robert Price, Feb 14 2015
EXAMPLE
a(2)=9 because 10^9 + 9 is prime.
MATHEMATICA
Do[If[Mod[n, 3]!=2&& PrimeQ[10^n+n], Print[n]], {n, 1, 15500, 2}] (* Farideh Firoozbakht, Jun 11 2006 *)
PROG
(PARI) is(n)=ispseudoprime(10^n+n) \\ Charles R Greathouse IV, Jun 12 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Shyam Sunder Gupta, Dec 27 2003
EXTENSIONS
One more term from Farideh Firoozbakht, Jun 11 2006
a(7) from Robert Price, Feb 14 2015
STATUS
approved