A092675 Primes of the form 80*R_k + 1, where R_k is the repunit (A002275) of length k.

881, 8888888888888888881, 8888888888888888888888888888888888888888888888888888888888888888888888888888881

Offset

1,1

Comments

Primes of the form 888...881.

The number of 8's in each term is given by the corresponding term of A056664 and so the first term too large to include above is 888...8881 (with 138 8's).

Primes of the form (8*10^k - 71)/9. - Vincenzo Librandi, Nov 16 2010

Links

Table of n, a(n) for n=1..3.

Makoto Kamada, Prime numbers of the form 88...881.

Index entries for primes involving repunits

Mathematica

Select[Table[10 FromDigits[PadRight[{}, n, 8]]+1, {n, 150}], PrimeQ] (* Harvey P. Dale, Aug 07 2019 *)

Crossrefs

Cf. A056664 (corresponding k).

Cf. A051200, A004022, A093176, A093177, A089346, A093174, A092571.

Sequence in context: A340342 A265181 A137064 * A135127 A338538 A230909

Adjacent sequences: A092672 A092673 A092674 * A092676 A092677 A092678

Keyword

bref,nonn

Author

Rick L. Shepherd, Mar 02 2004

Status

approved