

A103012


Numbers n such that 5*10^n + 3*R_n + 6 is prime, where R_n = 11...1 is the repunit (A002275) of length n.


1




OFFSET

1,3


COMMENTS

Also numbers n such that (16*10^n+17)/3 is prime.
a(10) > 10^5.  Robert Price, Sep 08 2015


LINKS

Table of n, a(n) for n=1..9.
Makoto Kamada, Prime numbers of the form 533...339.
Index entries for primes involving repunits.


FORMULA

a(n) = A101577(n1) + 1 for n>1.


EXAMPLE

For n=0, (16*10^n+17)/3=11 which is prime, so 0 is in the sequence.


MATHEMATICA

Do[ If[ PrimeQ[(16*10^n + 17)/3], Print[n]], {n, 0, 10000}]


CROSSREFS

Cf. A002275, A101577.
Sequence in context: A245745 A023331 A187923 * A166958 A112056 A033231
Adjacent sequences: A103009 A103010 A103011 * A103013 A103014 A103015


KEYWORD

nonn


AUTHOR

Robert G. Wilson v, Jan 18 2005


EXTENSIONS

a(9) from Kamada data by Robert Price, Dec 14 2010
Inserted a(1)=0 by Robert Price, Sep 08 2015


STATUS

approved



