A043525 Numbers having one 9 in base 10.

9, 19, 29, 39, 49, 59, 69, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 109, 119, 129, 139, 149, 159, 169, 179, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 209, 219, 229, 239, 249, 259, 269, 279, 289, 290, 291, 292, 293, 294, 295, 296, 297, 298, 309, 319

Offset: 1

Author

Clark Kimberling

Keywords

• nonn
• base

Links

• Enrique Pérez Herrero, Table of n, a(n) for n = 1..2000
• Index entries for 10-automatic sequences.

Crossrefs

Cf. A043489, A043493, A043497, A043501, A043505, A043509, A043513, A043517, A043521.

Cf. A011539, A140502.

Subsequence of A011539.

Programs

Mathematica

Select[Range[300],DigitCount[#,10,9]==1&] (* Harvey P. Dale, Jan 19 2013 *)

Python

def ok(n): return str(n).count('9') == 1
print(list(filter(ok, range(320)))) # Michael S. Branicky, Sep 19 2021

Formula

Sum_{n>=1} 1/a(n) = A140502. - Amiram Eldar, Nov 14 2020