OFFSET
1,1
COMMENTS
Also, numbers k such that (10^k - 31)/3 is prime.
Terms from Kamada data.
a(32) > 3*10^5.
LINKS
EXAMPLE
For k=4, 3*R_4 - 10 = 3333 - 10 = 3323 which is prime.
MATHEMATICA
Select[Range[0, 250000], PrimeQ[(10^# - 31)/3] &]
PROG
(Magma) [n: n in [2..310] | IsPrime((10^n-31) div 3)]; // Vincenzo Librandi, Apr 10 2015
CROSSREFS
KEYWORD
nonn,more,hard
AUTHOR
Robert Price, Apr 09 2015
EXTENSIONS
a(31) from Robert Price, Jul 12 2023
STATUS
approved