

A103014


Numbers n such that 5*10^n + 4*R_n  1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.


1



1, 3, 4, 9, 12, 60, 268, 289, 384, 795, 3474, 9180, 76438
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,2


COMMENTS

Also numbers n such that (49*10^n13)/9 is prime.
a(14) > 10^5.  Robert Price, Jul 16 2015


LINKS

Table of n, a(n) for n=1..13.
Makoto Kamada, Prime numbers of the form 544...443.
Index entries for primes involving repunits.


FORMULA

a(n) = A101579(n) + 1.


MATHEMATICA

Do[ If[ PrimeQ[(49*10^n  13)/9], Print[n]], {n, 0, 10000}]


CROSSREFS

Cf. A002275, A101579.
Sequence in context: A211221 A029448 A249179 * A116552 A339996 A225288
Adjacent sequences: A103011 A103012 A103013 * A103015 A103016 A103017


KEYWORD

more,nonn


AUTHOR

Robert G. Wilson v, Jan 18 2005


EXTENSIONS

a(13) from Robert Price, Jul 16 2015


STATUS

approved



