OFFSET
1,1
COMMENTS
Also numbers k such that (23*10^k + 13)/9 is prime.
a(18) > 10^5. - Robert Price, Feb 16 2015
LINKS
FORMULA
a(n) = A101962(n) + 1.
EXAMPLE
n = 2, 3, 26, 27 are members since 257, 2557, 255555555555555555555555557 and
2555555555555555555555555557 are primes.
MATHEMATICA
Do[ If[ PrimeQ[(23*10^n + 13)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Julien Peter Benney (jpbenney(AT)ftml.net), Nov 07 2004
EXTENSIONS
a(8), a(9), a(10) & a(11) from Sam Handler (sam_5_5_5_0(AT)yahoo.com), Nov 17 2004
a(12)-a(17) from Kamada data by Robert Price, Dec 14 2010
STATUS
approved