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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified December 6 03:02 EST 2016. Contains 278771 sequences.