

A103107


Numbers n such that 9*10^n + 8*R_n  7 is prime, where R_n = 11...1 is the repunit (A002275) of length n.


1



0, 6, 9, 90, 111, 210, 237, 414, 1192, 1260, 5836, 6772, 24861, 52431
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OFFSET

1,2


COMMENTS

Also numbers n such that (89*10^n71)/9 is prime.


LINKS



FORMULA

a(n) = A101016(n1) + 1, for n > 1.


MATHEMATICA

Do[ If[ PrimeQ[(89*10^n  71)/9], Print[n]], {n, 0, 10000}]


CROSSREFS



KEYWORD

more,nonn


AUTHOR



EXTENSIONS

Inserted a(1) = 0 and added a(14) from Robert Price, Nov 12 2015


STATUS

approved



