A089347 Primes of the form identical digits followed by a 1.

11, 31, 41, 61, 71, 331, 661, 881, 991, 2221, 3331, 4441, 6661, 33331, 99991, 333331, 3333331, 9999991, 33333331, 6666666661, 44444444441, 555555555551, 5555555555551, 7777777777771, 222222222222222221, 333333333333333331

Offset: 1

Author

Amarnath Murthy, Nov 05 2003

Keywords

• base
• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..80

Crossrefs

Cf. A089345, A089346.

Programs

Mathematica

Select[ FromDigits /@ Flatten[ Table[ PadLeft[{1}, i, # ] & /@ {1, 2, 3, 4, 5, 6, 7, 8, 9}, {i, 2, 18}], 1], PrimeQ[ # ] &] (* Robert G. Wilson v, Nov 15 2003 *)

Extensions

More terms from Ray Chandler and Robert G. Wilson v, Nov 07 2003