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A103040 Numbers n such that 6*10^n + 5*R_n + 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n. 1
1, 4, 9, 21, 48, 84, 696, 1489, 4167, 8400, 52099 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Also numbers n such that (59*10^n+13)/9 is prime.

a(12) > 10^5. - Robert Price, Sep 20 2015

LINKS

Table of n, a(n) for n=1..11.

Makoto Kamada, Prime numbers of the form 655...557.

Index entries for primes involving repunits.

FORMULA

a(n) = A101533(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(59*10^n + 13)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101533.

Sequence in context: A144527 A117880 A027973 * A084861 A122498 A132750

Adjacent sequences:  A103037 A103038 A103039 * A103041 A103042 A103043

KEYWORD

more,nonn,changed

AUTHOR

Robert G. Wilson v, Jan 18 2005

EXTENSIONS

a(11) from Robert Price, Sep 20 2015

STATUS

approved

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Last modified January 17 19:58 EST 2019. Contains 319251 sequences. (Running on oeis4.)