A093634 Primes of the form 9*10^k + R_k, where R_k is the repunit (A002275) of length k.

911, 911111, 911111111111111111111, 911111111111111111111111111111111111111111, 911111111111111111111111111111111111111111111111, 911111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111

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 k).

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