OFFSET
1,2
COMMENTS
Also, numbers k such that (682*10^k - 7)/9 is prime.
Terms from Kamada.
LINKS
EXAMPLE
For k=5, 7*R_7 - 2*10^5 = 7777777 - 200000 = 7577777 which is prime.
MATHEMATICA
Select[Range[0, 30000], PrimeQ[(682*10^#-7)/9 ] &]
PROG
(Magma) [n: n in [0..400] | IsPrime((682*10^n-7) div 9)]; // Vincenzo Librandi, Apr 15 2015
CROSSREFS
KEYWORD
more,hard,nonn
AUTHOR
Robert Price, Apr 14 2015
EXTENSIONS
a(18)-a(24) from Kamada data by Tyler Busby, Apr 16 2024
STATUS
approved