A103005 Numbers n such that 5*10^n + R_n + 2 is a prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 3, 19, 109, 129, 280, 387, 447, 487, 1048, 3298, 3460, 9454, 26103, 61693, 66469

Offset

1,2

Comments

Also numbers n such that (46*10^n+17)/9 is a prime.

a(17) > 10^5. - Robert Price, Jun 20 2015

Links

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

Makoto Kamada, Prime numbers of the form 511...113.

Index entries for primes involving repunits.

Formula

a(n) = A101570(n) + 1.

Mathematica

Do[ If[ PrimeQ[(46*10^n + 17)/9], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A101570.

Sequence in context: A240123 A130425 A334976 * A162354 A132959 A360230

Adjacent sequences: A103002 A103003 A103004 * A103006 A103007 A103008

Keyword

more,nonn

Author

Robert G. Wilson v, Jan 18 2005

Extensions

Addition of a(14) from Kamada data by Robert Price, Dec 12 2010

a(15)-a(16) from Robert Price, Jun 20 2015

Status

approved