

A100473


Numbers n such that 9*10^n + R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.


2



1, 17, 23, 73, 131, 473, 685, 701, 1909, 3029, 3473, 4193, 9931
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OFFSET

1,2


COMMENTS

Also numbers n such that (82*10^n+53)/9 is a prime.
Some of the larger entries may only correspond to probable primes.
a(14) > 10^5.  Robert Price, Oct 25 2015


LINKS

Table of n, a(n) for n=1..13.
Makoto Kamada, Prime numbers of the form 911...117.
Index entries for primes involving repunits.


FORMULA

a(n) = A100999(n) + 1.


EXAMPLE

n = 1, 17, so that 97 and 911111111111111117 are primes.


MATHEMATICA

Do[ If[ PrimeQ[(82*10^n + 53)/9], Print[n]], {n, 0, 10000}] (* Robert G. Wilson v, Jan 19 2005 *)


CROSSREFS

Cf. A002275, A100999.
Sequence in context: A043142 A043922 A260179 * A060252 A127924 A250640
Adjacent sequences: A100470 A100471 A100472 * A100474 A100475 A100476


KEYWORD

more,nonn


AUTHOR

Julien Peter Benney (jpbenney(AT)ftml.net), Nov 21 2004


EXTENSIONS

a(8)a(12) from Robert G. Wilson v, Jan 12 2005
a(13) from Robert G. Wilson v, Jan 12 2005


STATUS

approved



