OFFSET
1,2
COMMENTS
Also, numbers k such that (664*10^k - 7)/9 is prime.
Terms from Kamada.
a(6) > 30000.
LINKS
MATHEMATICA
Select[Range[0, 30000], PrimeQ[(664*10^#-7)/9 ] &]
PROG
(PARI) for(n=0, 100, if(isprime((664*10^n-7)/9), print1(n, ", "))) \\ Derek Orr, Apr 14 2015
(Magma) [n: n in [0..400] | IsPrime((664*10^n-7) div 9)]; // Vincenzo Librandi, Apr 15 2015
CROSSREFS
KEYWORD
more,hard,nonn
AUTHOR
Robert Price, Apr 14 2015
STATUS
approved