A093633 Primes of the form 8*10^k + R_k, where R_k is the repunit (A002275) of length k.

811, 8111, 811111111111111111111111111, 811111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111, 8111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111

Offset

1,1

Comments

The next term (a(6)) has 475 digits. - Harvey P. Dale, Sep 16 2016

Links

Table of n, a(n) for n=1..5.

Makoto Kamada, Prime numbers of the form 811...11.

Index entries for primes involving repunits

Mathematica

Select[Table[FromDigits[PadRight[{8}, n, 1]], {n, 150}], PrimeQ] (* Harvey P. Dale, Sep 16 2016 *)

Crossrefs

Cf. A002275, A056722 (corresponding k).

Sequence in context: A068278 A208189 A183216 * A045228 A252223 A158667

Adjacent sequences: A093630 A093631 A093632 * A093634 A093635 A093636

Keyword

nonn

Author

Rick L. Shepherd, Apr 06 2004

Status

approved