A102933 Numbers k such that 10^k + 3*R_k + 6 is prime, where R_k = 11...1 is the repunit (A002275) of length k.

1, 2, 4, 7, 10, 13, 14, 22, 23, 29, 38, 50, 53, 67, 104, 350, 376, 412, 1205, 1835, 2510, 2668, 6097, 8296, 14296, 43369, 127349, 142034

Offset

1,2

Comments

Also numbers k such that (4*10^k + 17)/3 is prime.

a(29) > 2*10^5. - Tyler Busby, Feb 01 2023

Links

Table of n, a(n) for n=1..28.

Makoto Kamada, Prime numbers of the form 133...339.

Index entries for primes involving repunits.

Formula

a(n) = A102014(n) + 1.

Mathematica

Do[ If[ PrimeQ[(4*10^n + 17)/3], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A102014.

Sequence in context: A007303 A102988 A080137 * A122019 A190279 A186325

Adjacent sequences: A102930 A102931 A102932 * A102934 A102935 A102936

Keyword

more,nonn

Author

Robert G. Wilson v, Dec 16 2004

Extensions

Addition of a(25) from Kamada data by Robert Price, Dec 08 2010

a(26) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013

a(27)-a(28) from Tyler Busby, Feb 01 2023

Status

approved