A099668 a(n) is the largest prime before A002282(n) repdigits.

7, 83, 887, 8887, 88883, 888887, 8888861, 88888883, 888888887, 8888888837, 88888888859, 888888888887, 8888888888857, 88888888888873, 888888888888883, 8888888888888753, 88888888888888801, 888888888888888859, 8888888888888888881, 88888888888888888879, 888888888888888888857

Offset: 1

Author

Labos Elemer, Nov 17 2004

Keywords

• base
• nonn

Examples

			n=2: 83 is before 88.
		

Crossrefs

Cf. A002282, A003618, A003617, A007917, A096497, A096498, A068104, A002275-A002283, A099656-A099667.

Programs

Mathematica

Table[NextPrime[8*(10^n-1)/9, -1], {n, 1, 35}]
Table[NextPrime[FromDigits[PadRight[{},n,8]],-1],{n,20}] (* Harvey P. Dale, Jul 12 2014 *)

Formula

a(n) = A007917(A002282(n)). - Amiram Eldar, Jun 29 2025