OFFSET
1,1
COMMENTS
a(13) > 10^5. - Robert Price, Mar 26 2015
MATHEMATICA
Select[Range[5000], PrimeQ[(10^# - 2 # + 1)] &] (* Vincenzo Librandi, Oct 05 2012 *)
PROG
(Magma) /* The code gives only the terms up to 354: */ [n: n in [1..600] | IsPrime(10^n-2*n+1) ]
(PARI) is(n)=ispseudoprime(10^n-2*n+1) \\ Charles R Greathouse IV, Feb 20 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Vincenzo Librandi, Mar 11 2010
EXTENSIONS
a(8)-a(10) from Vincenzo Librandi, Oct 05 2012
a(11)-a(12) from Robert Price, Mar 26 2015
STATUS
approved