login
A102950
Numbers k such that 2*10^k + R_k + 8 is prime, where R_k = 11...1 is the repunit (A002275) of length k.
1
1, 223, 318, 427, 3727, 5227, 8779, 11383, 15415, 26382
OFFSET
1,2
COMMENTS
Also numbers k such that (19*10^k + 71)/9 is prime.
a(11) > 10^5. - Robert Price, Feb 06 2015
FORMULA
a(n) = A101955(n) + 1.
MATHEMATICA
Do[ If[ PrimeQ[(19*10^n + 71)/9], Print[n]], {n, 0, 10000}]
CROSSREFS
Sequence in context: A271799 A152824 A142386 * A143801 A118818 A142437
KEYWORD
more,nonn
AUTHOR
Robert G. Wilson v, Dec 17 2004
EXTENSIONS
Addition of a(8)-a(10) from Kamada data by Robert Price, Dec 13 2010
STATUS
approved