OFFSET
1,1
COMMENTS
Also, numbers k such that (83*10^k + 61)/9 is prime.
Terms from Kamada data.
a(7) > 10^5.
LINKS
EXAMPLE
For k=2, 2*R_2 + 9*10^k + 7 = 22 + 900 + 7 = 929 which is prime.
MATHEMATICA
Select[Range[0, 100000], PrimeQ[(83*10^#+61)/9] &]
PROG
(Magma) [n: n in [0..300] | IsPrime((83*10^n+61) div 9)]; // _Vincenzo Librandi_, Jun 19 2015
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
_Robert Price_, Jun 18 2015
STATUS
approved