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A093944 Primes of the form 9*10^n + 7*R_n, where R_n is the repunit (A002275) of length n. 1
97, 977, 97777, 97777777777777777777, 97777777777777777777777777777, 97777777777777777777777777777777777777777777777777777777777777777777777777 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The next term has 204 digits. - Harvey P. Dale, May 22 2014

LINKS

Table of n, a(n) for n=1..6.

Makoto Kamada, Prime numbers of the form 977...77.

Index entries for primes involving repunits

MATHEMATICA

Select[Table[FromDigits[PadRight[{9}, n, 7]], {n, 250}], PrimeQ] (* Harvey P. Dale, May 22 2014 *)

CROSSREFS

Cf. A002275, A056727 (corresponding n).

Sequence in context: A262925 A093297 A068852 * A127748 A127828 A186075

Adjacent sequences:  A093941 A093942 A093943 * A093945 A093946 A093947

KEYWORD

nonn

AUTHOR

Rick L. Shepherd, Apr 17 2004

STATUS

approved

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Last modified May 14 13:20 EDT 2021. Contains 343884 sequences. (Running on oeis4.)