A103018 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.

1, 2, 3, 10, 25, 29, 34, 73, 76, 77, 651, 884, 938, 1252, 1893, 3342, 4034, 6168, 6216, 6231, 6812, 11046, 15448, 16628, 16918, 18734, 45935, 130393, 139289, 158819

Offset

1,2

Comments

Also numbers n such that (17*10^n+7)/3 is prime.

a(31) > 3*10^5. - Robert Price, Jul 13 2023

Links

Table of n, a(n) for n=1..30.

Makoto Kamada, Prime numbers of the form 566...669.

Index entries for primes involving repunits.

Formula

a(n) = A101583(n) + 1.

Mathematica

Do[ If[ PrimeQ[(17*10^n + 7)/3], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A101583.

Sequence in context: A295616 A059929 A123029 * A246437 A341265 A378424

Adjacent sequences: A103015 A103016 A103017 * A103019 A103020 A103021

Keyword

more,nonn

Author

Robert G. Wilson v, Jan 18 2005

Extensions

a(22)-a(26) from Kamada link by Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 01 2008

a(27) from Erik Branger May 01 2013 by Ray Chandler, Aug 16 2013

a(28)-a(30) from Robert Price, Jul 13 2023

Status

approved