

A103005


Numbers n such that 5*10^n + R_n + 2 is a prime, where R_n = 11...1 is the repunit (A002275) of length n.


1



1, 3, 19, 109, 129, 280, 387, 447, 487, 1048, 3298, 3460, 9454, 26103, 61693, 66469
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OFFSET

1,2


COMMENTS

Also numbers n such that (46*10^n+17)/9 is a prime.
a(17) > 10^5.  Robert Price, Jun 20 2015


LINKS

Table of n, a(n) for n=1..16.
Makoto Kamada, Prime numbers of the form 511...113.
Index entries for primes involving repunits.


FORMULA

a(n) = A101570(n) + 1.


MATHEMATICA

Do[ If[ PrimeQ[(46*10^n + 17)/9], Print[n]], {n, 0, 10000}]


CROSSREFS

Cf. A002275, A101570.
Sequence in context: A240123 A130425 A334976 * A162354 A132959 A253811
Adjacent sequences: A103002 A103003 A103004 * A103006 A103007 A103008


KEYWORD

more,nonn


AUTHOR

Robert G. Wilson v, Jan 18 2005


EXTENSIONS

Addition of a(14) from Kamada data by Robert Price, Dec 12 2010
a(15)a(16) from Robert Price, Jun 20 2015


STATUS

approved



