A103104 Numbers n such that 9*10^n + 6*R_n + 1 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 2, 4, 7, 13, 28, 58, 86, 92, 108, 1408, 1486, 1712, 2674, 3880, 5536, 7588, 7650, 10558, 15532, 17959, 37180, 93082

Offset

1,2

Comments

Also numbers n such that (29*10^n+1)/3 is prime.

a(24) > 10^5. - Robert Price, Nov 12 2015

Links

Table of n, a(n) for n=1..23.

Makoto Kamada, Prime numbers of the form 966...667.

Index entries for primes involving repunits.

Formula

a(n) = A101013(n) + 1.

Mathematica

Do[ If[ PrimeQ[(29*10^n + 1)/3], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A101013.

Sequence in context: A136408 A317718 A357931 * A103480 A024826 A291481

Adjacent sequences: A103101 A103102 A103103 * A103105 A103106 A103107

Keyword

more,nonn

Author

Robert G. Wilson v, Jan 19 2005

Extensions

a(19)-a(21) from Kamada data by Robert Price, Dec 14 2010

a(22) from Erik Branger May 01 2013 by Ray Chandler, Aug 17 2013

a(23) from Robert Price, Nov 12 2015

Status

approved