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A093634 Primes of the form 9*10^n + R_n, where R_n is the repunit (A002275) of length n. 1
911, 911111, 911111111111111111111, 911111111111111111111111111111111111111111, 911111111111111111111111111111111111111111111111, 911111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

Makoto Kamada, Prime numbers of the form 911...11.

H. C. Williams, Some primes with interesting digit patterns, Math. Comp. vol 32 no 144 (1978) pp 1306-1310, Table 2, r=9.

Index entries for primes involving repunits

MATHEMATICA

Select[Table[FromDigits[PadRight[{9}, n, 1]], {n, 60}], PrimeQ] (* Harvey P. Dale, Jun 18 2017 *)

CROSSREFS

Cf. A002275, A056726 (corresponding n).

Sequence in context: A068261 A119520 A145646 * A220984 A237084 A224969

Adjacent sequences:  A093631 A093632 A093633 * A093635 A093636 A093637

KEYWORD

nonn

AUTHOR

Rick L. Shepherd, Apr 06 2004

EXTENSIONS

One more term from Harvey P. Dale, Jun 18 2017

STATUS

approved

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Last modified October 22 15:11 EDT 2018. Contains 316490 sequences. (Running on oeis4.)