OFFSET
1,2
COMMENTS
Also, numbers k such that (10^k + 119)/3 is prime.
Terms from Kamada data. Note Kamada does not recognize k=1 as 43 is a degenerate case of form AAA..ABA.
a(26) > 3*10^5.
LINKS
EXAMPLE
For k=3, 3*R_3 + 40 = 333 + 40 = 373 which is prime.
MATHEMATICA
Select[Range[0, 250000], PrimeQ[(10^# + 119)/3] &]
PROG
(PARI) is(n)=ispseudoprime(10^n\3+40) \\ Charles R Greathouse IV, Apr 10 2015
(Magma) [n: n in [0..400] | IsPrime((10^n+119) div 3)]; // Vincenzo Librandi, Apr 11 2015
CROSSREFS
KEYWORD
more,hard,nonn
AUTHOR
Robert Price, Apr 10 2015
STATUS
approved