OFFSET
1,1
COMMENTS
Also numbers k such that (73*10^k - 1)/9 is prime.
The next term is > 10000. - Hugo Pfoertner, Oct 21 2004
a(18) > 250000. - Robert Price, Jan 21 2015
LINKS
MATHEMATICA
Do[ If[ PrimeQ[ 8*10^n + (10^n-1)/9], Print[n]], {n, 0, 5000}]
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Robert G. Wilson v, Aug 11 2000
EXTENSIONS
a(12)-a(17) from Kamada data by Robert Price, Jan 21 2015
STATUS
approved