A103039 Numbers n such that 6*10^n + 5*R_n - 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

2, 3, 9, 11, 12, 15, 36, 38, 41, 77, 90, 96, 132, 374, 399, 617, 1332, 1395, 1811, 2804, 4953, 5310, 16676, 29336

Offset

1,1

Comments

Also numbers n such that (59*10^n-23)/9 is prime.

a(25) > 10^5. - Robert Price, Sep 14 2015

Links

Table of n, a(n) for n=1..24.

Makoto Kamada, Prime numbers of the form 655...553.

Index entries for primes involving repunits.

Formula

a(n) = A101532(n) + 1.

Mathematica

Do[ If[ PrimeQ[(59*10^n - 23)/9], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A101532.

Sequence in context: A063257 A229492 A328970 * A140222 A272537 A121557

Adjacent sequences: A103036 A103037 A103038 * A103040 A103041 A103042

Keyword

more,nonn

Author

Robert G. Wilson v, Jan 18 2005

Extensions

a(23)-a(24) from Kamada data by Robert Price, Dec 14 2010

Status

approved