

A103019


Numbers n such that 5*10^n + 7*R_n  6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.


1



2, 6, 9, 27, 30, 48, 141, 150, 372, 422, 1097, 3570, 4607, 5289, 10734, 11550, 32604, 42470, 46311, 67578
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OFFSET

1,1


COMMENTS

Also numbers n such that (52*10^n61)/9 is prime.
a(21) > 10^5.  Robert Price, Sep 05 2015


LINKS

Table of n, a(n) for n=1..20.
Makoto Kamada, Prime numbers of the form 577...771.
Index entries for primes involving repunits.


FORMULA

a(n) = A101584(n) + 1.


MATHEMATICA

Do[ If[ PrimeQ[(52*10^n  61)/9], Print[n]], {n, 0, 10000}]


CROSSREFS

Cf. A002275, A101584.
Sequence in context: A243558 A244427 A121624 * A101823 A242421 A093397
Adjacent sequences: A103016 A103017 A103018 * A103020 A103021 A103022


KEYWORD

more,nonn


AUTHOR

Robert G. Wilson v, Jan 18 2005


EXTENSIONS

Addition of a(15)a(16) from Kamada data by Robert Price, Dec 12 2010
a(17)a(19) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013
a(20) from Robert Price, Sep 05 2015


STATUS

approved



