A103046 Numbers n such that 6*10^n + 8*R_n - 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

0, 1, 33, 72, 177, 192, 325, 417, 732, 1362, 13947, 14887, 32706, 63954, 64783, 82377

Offset

1,3

Comments

Also numbers n such that (62*10^n-17)/9 is prime.

a(17) > 10^5. - Robert Price, Sep 15 2015

Links

Table of n, a(n) for n=1..16.

Makoto Kamada, Prime numbers of the form 688...887.

Index entries for primes involving repunits.

Formula

a(n) = A101539(n-1) + 1 for n>1.

Mathematica

Do[ If[ PrimeQ[(62*10^n - 17)/9], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A101539.

Sequence in context: A044135 A044516 A015722 * A063868 A184417 A240884

Adjacent sequences: A103043 A103044 A103045 * A103047 A103048 A103049

Keyword

more,nonn

Author

Robert G. Wilson v, Jan 18 2005

Extensions

a(11)-a(12) from Kamada data by Robert Price, Dec 14 2010

a(13) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013

Inserted a(1)=0 by Robert Price, Sep 15 2015

a(14)-a(16) from Robert Price, Sep 15 2015

Status

approved