

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




OFFSET

1,2


COMMENTS

Also numbers k such that (19*10^k + 71)/9 is prime.


LINKS



FORMULA



MATHEMATICA

Do[ If[ PrimeQ[(19*10^n + 71)/9], Print[n]], {n, 0, 10000}]


CROSSREFS



KEYWORD

more,nonn


AUTHOR



EXTENSIONS

Addition of a(8)a(10) from Kamada data by Robert Price, Dec 13 2010


STATUS

approved



