

A102979


Numbers n such that 3*10^n + 8*R_n  1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.


1




OFFSET

1,3


COMMENTS

Also numbers n such that (35*10^n17)/9 is prime.
a(6) > 10^5.  Robert Price, Mar 30 2015


LINKS

Table of n, a(n) for n=1..5.
Makoto Kamada, Prime numbers of the form 388...887.
Index entries for primes involving repunits.


FORMULA

a(n) = A101846(n1) + 1.


MATHEMATICA

Do[ If[ PrimeQ[(35*10^n  17)/9], Print[n]], {n, 0, 10000}]


CROSSREFS

Cf. A002275, A101846.
Sequence in context: A172733 A329911 A088021 * A069942 A261823 A146202
Adjacent sequences: A102976 A102977 A102978 * A102980 A102981 A102982


KEYWORD

more,nonn


AUTHOR

Robert G. Wilson v, Dec 17 2004


EXTENSIONS

Additional term 10176 (a PRP) from Serge Batalov, Oct 12 2008
Addition of a(5) from Kamada data by Robert Price, Dec 13 2010


STATUS

approved



