A370919 Positive integers whose ternary representation includes at least one 1, and every 1 is followed by 2.

5, 15, 17, 23, 45, 47, 50, 51, 53, 59, 69, 71, 77, 135, 137, 140, 141, 143, 150, 152, 153, 155, 158, 159, 161, 167, 177, 179, 185, 207, 209, 212, 213, 215, 221, 231, 233, 239, 405, 407, 410, 411, 413, 420, 422, 423, 425, 428, 429, 431, 450, 452, 455, 456

Offset: 1

Author

Clark Kimberling, Mar 16 2024

Keywords

• nonn
• base

Examples

			The ternary representations of 5, 15, and 17 are 12, 120, and 122.
		

Crossrefs

Cf. A007089, A081606.

Cf. A370916, A370917, A370918, A370920, A370921, A370922, A370923.

Programs

Mathematica

Map[#[[1]] &, Select[Map[{#, #[[1]] > 0 && #[[1]] == #[[2]] &[{Length[
StringCases[#, "1"]], Length[StringCases[#, "12"]]}] &[
IntegerString[#, 3]]} &, Range[500]], #[[2]] &]]   (* Peter J. C. Moses, Mar 05 2024 *)