OFFSET
1,1
COMMENTS
Also numbers k such that (25*10^k - 61)/9 is prime.
a(12) > 10^5. - Robert Price, Feb 27 2015
LINKS
FORMULA
a(n) = A101966(n) + 1.
EXAMPLE
For n = 2 and 6, we get 271 and 2777771 which are primes.
MATHEMATICA
Do[ If[ PrimeQ[(25*10^n - 61)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Julien Peter Benney (jpbenney(AT)ftml.net), Oct 22 2004
EXTENSIONS
a(6) from Ray Chandler, Nov 04 2004
a(7), a(8) & a(9) from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 03 2004
Addition of a(10) from Kamada data by Robert Price, Dec 13 2010
a(11) from Robert Price, Feb 27 2015
STATUS
approved