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A093171 Primes of the form 80*R_k + 7, where R_k is the repunit (A002275) of length k. 4
7, 887, 8887, 888887, 888888887, 888888888887, 888888888888888888888888888888888888888888888888888888888888888888888887 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes of the form (8*10^k - 17)/9. - Vincenzo Librandi, Nov 16 2010

LINKS

Table of n, a(n) for n=1..7.

Makoto Kamada, Prime numbers of the form 88...887.

Index entries for primes involving repunits

CROSSREFS

Cf. A056695 (corresponding k), A096846.

Sequence in context: A193342 A298301 A332187 * A330295 A177908 A127102

Adjacent sequences: A093168 A093169 A093170 * A093172 A093173 A093174

KEYWORD

nonn

AUTHOR

Rick L. Shepherd, Mar 26 2004

STATUS

approved

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Last modified February 4 20:58 EST 2023. Contains 360082 sequences. (Running on oeis4.)