A099667 a(n) is the largest prime before A002281(n); repdigits repeating 7.

5, 73, 773, 7759, 77773, 777769, 7777769, 77777761, 777777773, 7777777741, 77777777767, 777777777773, 7777777777771, 77777777777753, 777777777777773, 7777777777777753, 77777777777777747, 777777777777777743

Offset: 1

Author

Labos Elemer, Nov 17 2004

Keywords

• base
• nonn

Examples

			n=2: 73 is before 77.
		

Links

• Michael De Vlieger, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A003618, A003617, A096497, A096498, A068104, A002275-A002283, A099656-A099668.

Programs

Mathematica

Table[NextPrime[7 (10^n - 1)/9, -1], {n, 35}]
(* Second program: *)
Rest[NextPrime[#,-1]&/@LinearRecurrence[{11,-10},{0,7},25]] (* Harvey P. Dale, May 24 2015 *)

Extensions

Name changed by David A. Corneth, Sep 01 2017