A099663 a[n] is the largest prime before A002276[n] repdigits.

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

Offset

2,1

Links

Table of n, a(n) for n=2..18.

Example

n=2: 19 is before 22.

Mathematica

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

Crossrefs

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

Sequence in context: A032613 A199132 A201791 * A202665 A115854 A220978

Adjacent sequences: A099660 A099661 A099662 * A099664 A099665 A099666

Keyword

base,nonn

Author

Labos Elemer, Nov 17 2004

Status

approved