OFFSET
1,2
COMMENTS
Also numbers k such that (8*10^(k+1)-17)/9 is prime.
a(21) > 10^5. - Robert Price, May 20 2014
LINKS
FORMULA
a(n) = A096846(n) - 1.
MATHEMATICA
Do[ If[ PrimeQ[80*(10^n - 1)/9 + 7], Print[n]], {n, 0, 5000}]
CROSSREFS
KEYWORD
hard,nonn,more
AUTHOR
Robert G. Wilson v, Aug 10 2000
EXTENSIONS
More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008
a(18)-a(20) derived from A096846 by Robert Price, May 20 2014
STATUS
approved