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A093404 Primes of the form 70*R_n + 9, where R_n is the repunit (A002275) of length n. 3
79, 777777777777777777777777777777777777777777777777777777777777777779, 77777777777777777777777777777777777777777777777777777777777777777777777777777777777779, 777777777777777777777777777777777777777777777777777777777777777777777777777777777777777779 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Primes of the form (7*10^n + 11)/9. - Vincenzo Librandi, Nov 16 2010

LINKS

Table of n, a(n) for n=1..4.

Makoto Kamada, Prime numbers of the form 77...779.

Index entries for primes involving repunits

MATHEMATICA

Select[Table[FromDigits[PadLeft[{9}, n, 7]], {n, 100}], PrimeQ] (* Harvey P. Dale, May 09 2012 *)

CROSSREFS

Cf. A002275, A056693 (corresponding n), A098089.

Sequence in context: A060711 A128472 A243432 * A236236 A031136 A050456

Adjacent sequences:  A093401 A093402 A093403 * A093405 A093406 A093407

KEYWORD

nonn

AUTHOR

Rick L. Shepherd, Mar 28 2004

STATUS

approved

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Last modified April 12 17:48 EDT 2021. Contains 342929 sequences. (Running on oeis4.)