A099663 a(n) is the largest prime before A002276(n).

19, 211, 2221, 22193, 222199, 2222219, 22222199, 222222193, 2222222137, 22222222189, 222222222169, 2222222222197, 22222222222201, 222222222222151, 2222222222222203, 22222222222222153, 222222222222222221, 2222222222222222177, 22222222222222222169, 222222222222222222149, 2222222222222222222161

Offset: 2

Author

Labos Elemer, Nov 17 2004

Keywords

• base
• nonn

Examples

			n=2: 19 is before 22.
		

Crossrefs

Cf. A007917, A002276.

Cf. A003618, A003617, A096497, A096498, A068104, A002275-A002283, A099656-A099669.

Programs

Mathematica

Table[NextPrime[2(10^n-1)/9, -1], {n, 2, 35}]
Drop[NextPrime[#,-1]&/@LinearRecurrence[{11,-10},{0,2},20],2] (* Harvey P. Dale, Dec 19 2020 *)

Formula

a(n) = A007917(A002276(n)). - Michel Marcus, Jun 29 2025

Extensions

More terms from Michel Marcus, Jun 29 2025