

A103097


Numbers n such that 9*10^n + 4*R_n  3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.


1




OFFSET

1,1


COMMENTS

Also numbers n such that (85*10^n31)/9 is prime.
a(10) > 10^5.  Robert Price, Nov 07 2015


LINKS

Table of n, a(n) for n=1..9.
Makoto Kamada, Prime numbers of the form 944...441.
Index entries for primes involving repunits.


FORMULA

a(n) = A101006(n) + 1.


MATHEMATICA

Do[ If[ PrimeQ[(85*10^n  31)/9], Print[n]], {n, 0, 10000}]


CROSSREFS

Cf. A002275, A101006.
Sequence in context: A012456 A071686 A296742 * A335750 A062286 A071071
Adjacent sequences: A103094 A103095 A103096 * A103098 A103099 A103100


KEYWORD

more,nonn


AUTHOR

Robert G. Wilson v, Jan 19 2005


EXTENSIONS

a(7)a(8) from Kamada data by Robert Price, Dec 14 2010
a(9) from Robert Price, Nov 07 2015


STATUS

approved



