

A102983


Numbers n such that 4*10^n + R_n + 8 is prime, where R_n = 11...1 is the repunit (A002275) of length n.


1




OFFSET

1,1


COMMENTS

Also numbers n such that (37*10^n+71)/9 is prime.
a(10) > 10^5.  Robert Price, Apr 14 2015


LINKS

Table of n, a(n) for n=1..9.
Makoto Kamada, Prime numbers of the form 411...119.
Index entries for primes involving repunits.


FORMULA

a(n) = A101718(n) + 1.


MATHEMATICA

Do[ If[ PrimeQ[(37*10^n + 71)/9], Print[n]], {n, 0, 10000}]


PROG

(MAGMA) [n: n in [0..300]  IsPrime((37*10^n+71) div 9)]; // Vincenzo Librandi, Apr 15 2015


CROSSREFS

Cf. A002275, A101718.
Sequence in context: A183291 A254405 A216847 * A038583 A082080 A127997
Adjacent sequences: A102980 A102981 A102982 * A102984 A102985 A102986


KEYWORD

more,nonn


AUTHOR

Robert G. Wilson v, Dec 21 2004


EXTENSIONS

Addition of a(7)a(8) from Kamada data by Robert Price, Dec 13 2010
a(9) from Robert Price, Apr 14 2015


STATUS

approved



