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

1,1

Links

Table of n, a(n) for n=1..54.

Example

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

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 *)

Crossrefs

Cf. A007089, A081606.

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

Sequence in context: A166503 A231720 A134453 * A174598 A022417 A102180

Adjacent sequences: A370916 A370917 A370918 * A370920 A370921 A370922

Keyword

nonn,base

Author

Clark Kimberling, Mar 16 2024

Status

approved