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A103104 Numbers n such that 9*10^n + 6*R_n + 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
1, 2, 4, 7, 13, 28, 58, 86, 92, 108, 1408, 1486, 1712, 2674, 3880, 5536, 7588, 7650, 10558, 15532, 17959, 37180 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (29*10^n+1)/3 is prime.

LINKS

Table of n, a(n) for n=1..22.

Makoto Kamada, Factorizations of 966...667.

Index entries for primes involving repunits.

MATHEMATICA

Do[ If[ PrimeQ[(29*10^n + 1)/3], Print[n]], {n, 0, 10000}]

CROSSREFS

Sequence in context: A025246 A112740 A136408 * A103480 A024826 A102114

Adjacent sequences:  A103101 A103102 A103103 * A103105 A103106 A103107

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Jan 19 2005

EXTENSIONS

a(19)-a(21) from Kamada data by Robert Price, Dec 14 2010

a(22) from Erik Branger May 01 2013 by Ray Chandler, Aug 17 2013

STATUS

approved

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Last modified December 21 13:45 EST 2014. Contains 252321 sequences.