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A103039 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
2, 3, 9, 11, 12, 15, 36, 38, 41, 77, 90, 96, 132, 374, 399, 617, 1332, 1395, 1811, 2804, 4953, 5310, 16676, 29336 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Also numbers n such that (59*10^n-23)/9 is prime.

a(25) > 10^5. - Robert Price, Sep 14 2015

LINKS

Table of n, a(n) for n=1..24.

Makoto Kamada, Prime numbers of the form 655...553.

Index entries for primes involving repunits.

FORMULA

a(n) = A101532(n) + 1.

MATHEMATICA

Do[ If[ PrimeQ[(59*10^n - 23)/9], Print[n]], {n, 0, 10000}]

CROSSREFS

Cf. A002275, A101532.

Sequence in context: A063257 A229492 A328970 * A140222 A272537 A121557

Adjacent sequences:  A103036 A103037 A103038 * A103040 A103041 A103042

KEYWORD

more,nonn

AUTHOR

Robert G. Wilson v, Jan 18 2005

EXTENSIONS

a(23)-a(24) from Kamada data by Robert Price, Dec 14 2010

STATUS

approved

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Last modified November 14 07:19 EST 2019. Contains 329111 sequences. (Running on oeis4.)