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A103094 Numbers n such that 9*10^n + 2*R_n + 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
5, 29, 60, 147, 186, 456, 678, 1373, 3378, 15726 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also numbers n such that (83*10^n+7)/9 is prime.

LINKS

Table of n, a(n) for n=1..10.

Makoto Kamada, Factorizations of 922...223.

Index entries for primes involving repunits.

MATHEMATICA

Do[ If[ PrimeQ[(83*10^n + 7)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Sequence in context: A177831 A115706 A031394 * A108928 A097812 A176333

Adjacent sequences:  A103091 A103092 A103093 * A103095 A103096 A103097

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Jan 19 2005

EXTENSIONS

a(10) from Kamada data by Robert Price, Dec 14 2010

STATUS

approved

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Last modified November 23 19:50 EST 2014. Contains 249865 sequences.