

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, 68231
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OFFSET

1,1


COMMENTS

Also numbers n such that (83*10^n+7)/9 is prime.
a(12) > 10^5.  Robert Price, Oct 31 2015


LINKS

Table of n, a(n) for n=1..11.
Makoto Kamada, Prime numbers of the form 922...223.
Index entries for primes involving repunits.


FORMULA

a(n) = A101002(n) + 1.


MATHEMATICA

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


CROSSREFS

Cf. A002275, A101002.
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
a(11) from Robert Price, Oct 31 2015


STATUS

approved



