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A103010 Numbers n such that 5*10^n + 2*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
3, 5, 33, 48, 59, 60, 74, 126, 177, 228, 638, 1304, 1644, 2435, 4374, 8750, 15114, 16853 (list; graph; refs; listen; history; internal format)
OFFSET

1,1

COMMENTS

Also numbers n such that (47*10^n+43)/9 is prime.

LINKS

Makoto Kamada, Factorizations of 522...227.

Index entries for primes involving repunits.

MATHEMATICA

Do[ If[ PrimeQ[(46*10^n + 43)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Sequence in context: A109173 A179387 A199774 * A187993 A068111 A162444

Adjacent sequences:  A103007 A103008 A103009 * A103011 A103012 A103013

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v (rgwv(AT)rgwv.com), Jan 18 2005

EXTENSIONS

a(17)-a(18) from Kamada data by Robert Price (pamandbobprice(AT)yahoo.com), Dec 14 2010

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Last modified February 14 00:26 EST 2012. Contains 205567 sequences.