OFFSET
1,1
COMMENTS
Also, numbers k such that 96*10^k - 1 is prime.
Terms from Kamada.
846519 reported to Kamada by Bruno DallOsto is also in this sequence. It may or may not be a(31).
a(31) > 230000.
LINKS
EXAMPLE
For k=10, 9*R_12 - 4*10^10 = 999999999999 - 40000000000 = 959999999999 which is prime.
MATHEMATICA
Select[Range[0, 230000], PrimeQ[96*10^#-1 ] &]
PROG
(Magma) [n: n in [0..400] | IsPrime(96*10^n-1)]; // Vincenzo Librandi, Apr 15 2015
CROSSREFS
KEYWORD
more,hard,nonn
AUTHOR
Robert Price, Apr 14 2015
STATUS
approved