A103037 Numbers n such that 6*10^n + 4*R_n + 5 is prime, where R_n = 11...1 is the repunit (A002275) of length n.

0, 3, 105, 627, 687, 699, 5715, 11391, 11673

Offset

1,2

Comments

Also numbers n such that (58*10^n+41)/9 is prime.

a(10) > 10^5. - Robert Price, Sep 11 2015

Links

Table of n, a(n) for n=1..9.

Makoto Kamada, Prime numbers of the form 644...449.

Index entries for primes involving repunits.

Formula

a(n) = A101530(n-1) + 1 for n>1.

Example

For n=0, (58*10^n+41)/9=11 which is prime, so 0 is in the sequence.

Mathematica

Do[ If[ PrimeQ[(58*10^n + 41)/9], Print[n]], {n, 0, 10000}]

Crossrefs

Cf. A002275, A101530.

Sequence in context: A050651 A233251 A279303 * A228309 A215945 A350986

Adjacent sequences: A103034 A103035 A103036 * A103038 A103039 A103040

Keyword

more,nonn

Author

Robert G. Wilson v, Jan 18 2005

Extensions

a(8)-a(9) from Kamada data by Robert Price, Dec 14 2010

Inserted a(1)=0 by Robert Price, Sep 11 2015

Status

approved