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A103091 Numbers n such that 8*10^n + 7*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 2
1, 3, 6, 31, 36, 61, 117, 229, 339, 3165, 3958, 5277, 5343, 6079, 6535, 8485, 15084 (list; graph; refs; listen; history; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (79*10^n+11)/9 is prime.

LINKS

Makoto Kamada, Factorizations of 877...779.

Index entries for primes involving repunits.

MATHEMATICA

Do[ If[ PrimeQ[(79*10^n + 11)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Sequence in context: A002164 A117805 A154135 * A186940 A101751 A133665

Adjacent sequences:  A103088 A103089 A103090 * A103092 A103093 A103094

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 19 2005

EXTENSIONS

a(17) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 14 2010

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Last modified February 14 05:09 EST 2012. Contains 205570 sequences.