A103095 Numbers n such that 9*10^n + 2*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

1, 3, 4, 15, 153, 322, 471, 561, 664, 2157, 3697, 14875, 19270, 22095

Offset

1,2

Comments

Also numbers n such that (83*10^n+43)/9 is prime.

a(15) > 10^5. - Robert Price, Nov 02 2015

Links

Table of n, a(n) for n=1..14.

Makoto Kamada, Prime numbers of the form 922...227.

Index entries for primes involving repunits.

Formula

a(n) = A101003(n) + 1.

Mathematica

Do[ If[ PrimeQ[(83*10^n + 43)/9], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A101003.

Sequence in context: A115752 A346974 A354395 * A041325 A042541 A325212

Adjacent sequences: A103092 A103093 A103094 * A103096 A103097 A103098

Keyword

more,nonn

Author

Robert G. Wilson v, Jan 19 2005

Extensions

a(12)-a(14) from Kamada data by Robert Price, Dec 14 2010

Status

approved