OFFSET
1,2
COMMENTS
Also numbers k such that (4*10^(k+1)-31)/9 is prime.
LINKS
FORMULA
a(n) = A099412(n+1) - 1. - Robert Price, Jan 30 2015
MATHEMATICA
Do[ If[ PrimeQ[40*(10^n - 1)/9 + 1], Print[n]], {n, 0, 7000}]
CROSSREFS
KEYWORD
hard,nonn
AUTHOR
Robert G. Wilson v, Aug 10 2000
EXTENSIONS
a(11)-a(16) derived from A099412 by Robert Price, Jan 30 2015
STATUS
approved