A103017 Numbers n such that 5*10^n + 6*R_n - 3 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

0, 1, 2, 4, 7, 22, 28, 36, 109, 155, 868, 1777, 2465, 3874, 4506, 4684, 5503, 13975, 15632, 33054, 34307, 50495, 60631, 62328, 92513, 92869

Offset

1,3

Comments

Also numbers n such that (17*10^n-11)/3 is prime.

a(27) > 10^5. - Robert Price, Jul 29 2015

Links

Table of n, a(n) for n=1..26.

Makoto Kamada, Prime numbers of the form 566...663.

Index entries for primes involving repunits.

Formula

a(n) = A101582(n-1) + 1 for n>1.

Mathematica

Do[ If[ PrimeQ[(17*10^n - 11)/3], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A101582.

Sequence in context: A337062 A153550 A102984 * A091833 A171978 A290571

Adjacent sequences: A103014 A103015 A103016 * A103018 A103019 A103020

Keyword

more,nonn

Author

Robert G. Wilson v, Jan 18 2005

Extensions

a(18)-a(19) from Kamada data by Robert Price, Dec 14 2010

a(20)-a(21) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013

Prepended a(1)=0 by Robert Price, Jul 29 2015

a(22)-a(26) from Robert Price, Jul 29 2015

Status

approved