OFFSET
1,2
COMMENTS
a(26) > 10^5. - Robert Price, Mar 28 2016
MATHEMATICA
Do[ If[ PrimeQ[10^n + 9^(n - 1)], Print[n]], {n, 4000}]
PROG
(PARI) is(n)=isprime(10^n+9^(n-1)) \\ Charles R Greathouse IV, Feb 17 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
Herman H. Rosenfeld (herm3(AT)pacbell.net) and Robert G. Wilson v, Jun 21 2004
EXTENSIONS
a(17)-a(25) from Robert Price, Mar 28 2016
STATUS
approved