A370920 Positive integers in whose ternary representation 2 occurs at least once, and every 2 is followed by 0.

6, 15, 18, 19, 33, 42, 45, 46, 54, 55, 57, 58, 60, 87, 96, 99, 100, 114, 123, 126, 127, 135, 136, 138, 139, 141, 162, 163, 165, 166, 168, 171, 172, 174, 175, 177, 180, 181, 249, 258, 261, 262, 276, 285, 288, 289, 297, 298, 300, 301, 303, 330, 339, 342, 343

Offset: 1

Author

Clark Kimberling, Mar 16 2024

Keywords

• nonn
• base

Crossrefs

Cf. A007089, A074940.

Cf. A370916, A370917, A370918, A370919, A370921, A370922, A370923.

Programs

Mathematica

Map[#[[1]] &, Select[Map[{#, #[[1]] > 0 && #[[1]] == #[[2]] &[{Length[
StringCases[#, "2"]], Length[StringCases[#, "20"]]}] &[
IntegerString[#, 3]]} &, Range[500]], #[[2]] &]]   (* Peter J. C. Moses, Mar 05 2024 *)

Formula

The ternary representations of 6, 15, and 18 are 20, 120, and 200.