OFFSET
1,1
COMMENTS
Also, numbers k such that 95*10^k - 1 is prime.
Terms from Kamada.
a(9) > 1170000.
LINKS
EXAMPLE
For k=3, 9*R_5 - 5*10^3 = 99999 - 5000 = 94999 which is prime.
MATHEMATICA
Select[Range[0, 1170000], PrimeQ[95*10^#-1 ] &]
PROG
(Magma) [n: n in [0..400] | IsPrime(95*10^n-1)]; // Vincenzo Librandi, Apr 15 2015
CROSSREFS
KEYWORD
more,hard,nonn
AUTHOR
Robert Price, Apr 14 2015
STATUS
approved