

A103056


Numbers n such that 7*10^n + 3*R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.


1



0, 1, 2, 5, 7, 85, 345, 1595, 2105, 6386, 9119, 9332, 14707, 72560
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OFFSET

1,3


COMMENTS

Also numbers n such that (22*10^n+17)/3 is prime.


LINKS



FORMULA



EXAMPLE

For n=0, (22*10^n+17)/3 = 13 which is a prime so 0 is a term.


MATHEMATICA

Do[ If[ PrimeQ[(22*10^n + 17)/3], Print[n]], {n, 0, 10000}]


CROSSREFS



KEYWORD

more,nonn


AUTHOR



EXTENSIONS



STATUS

approved



